Homogeneously branched ethylene polymer carpet, carpet backing and method for making same

ABSTRACT

The present invention pertains to carpet and methods of making carpet. In one aspect, the carpet includes (a) a primary backing which has a face and a back surface, (b) a plurality of fibers attached to the primary backing and extending from the face of the primary backing and exposed at the back surface of the primary backing, (c) an adhesive backing, (d) an optional secondary backing adjacent to the adhesive backing, and (e) at least one homogeneously branched ethylene polymer. The method includes extrusion coating at least one homogeneously branched ethylene polymer onto the back surface of a primary backing to provide an adhesive backing. The method can include additional steps or procedures, either separately or in various combinations. Additional steps and procedures include washing or scouring the primary backing and fibers prior to the extrusion step, and utilizing implosion agents. The preferred homogeneously branched ethylene polymer is a substantially linear ethylene polymer. The constructions and methods described herein are particularly suited for making tufted, broad-loom carpet having improved abrasion resistance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application from U.S.Provisional Application No. 60/039,412, filed Feb. 28, 1997, which wasrelated to: Ser. No. 60/039,217, entitled “ETHYLENE POLYMER CARPET,CARPET BACKINGS AND METHODS”; Ser. No. 60/039,411 entitled “CARPETS,CARPET BACKINGS AND METHODS USING SUBSTANTIALLY LINEAR ETHYLENE POLYMERSMETHODS”; Ser. No. 60/039,584 entitled “CARPET BACKINGS AND METHODSUSING SUBSTANTIALLY LINEAR ETHYLENE POLYMERS METHODS”; and Ser. No.60/039,587 entitled “CARPET BACKINGS AND METHODS USING HOMOGENEOUSLINEAR ETHYLENE POLYMERS,” all five of which were filed on Feb. 28,1997, the disclosures of all of which are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to carpets and methods of making carpets,wherein, for each, the carpets comprise at least one flexible ethylenepolymer backing material. In a particular instance, the inventionrelates to a carpet and a method of making a carpet by an extrusioncoating technique, wherein for each the carpet comprises a backingmaterial comprised of at least one homogeneously branched ethylenepolymer.

BACKGROUND OF THE INVENTION

The present invention pertains to any carpet constructed with a primarybacking material and includes tufted carpet and non-tufted carpet suchas needle punched carpet. Although specific embodiments are amenable totufted and non-tufted carpet, tufted carpet is preferred.

As illustrated in FIG. 1, tufted carpets are composite structures whichinclude yarn (which is also known as a fiber bundle), a primary backingmaterial having a face surface and a back surface, an adhesive backingmaterial and, optionally, a secondary backing material. To form the facesurface of tufted carpet, yarn is tufted through the primary backingmaterial such that the longer length of each stitch extends through theface surface of the primary backing material. Typically, the primarybacking material is made of a woven or non-woven material such as athermoplastic polymer, most commonly polypropylene.

The face of a tufted carpet can generally be made in three ways. First,for loop pile carpet, the yarn loops formed in the tufting process areleft intact. Second, for cut pile carpet, the yarn loops are cut, eitherduring tufting or after, to produce a pile of single yarn ends insteadof loops. Third, some carpet styles include both loop and cut pile. Onevariety of this hybrid is referred to as tip-sheared carpet where loopsof differing lengths are tufted followed by shearing the carpet at aheight so as to produce a mix of uncut, partially cut, and completelycut loops. Alternatively, the tufting machine can be configured so as tocut only some of the loops, thereby leaving a pattern of cut and uncutloops. Whether loop, cut, or a hybrid, the yarn on the back side of theprimary backing material comprises tight, unextended loops.

The combination of tufted yarn and a primary backing material withoutthe application of an adhesive backing material or secondary backingmaterial is referred to in the carpet industry as raw tufted carpet orgreige goods. Greige goods become finished tufted carpet with theapplication of an adhesive backing material and an optional secondarybacking material to the back side of the primary backing material.Finished tufted carpet can be prepared as broad-loomed carpet in rollstypically 6 or 12 feet wide. Alternatively, carpet can be prepared ascarpet tiles, typically 18 inches square in the United States and 50 cm.square elsewhere.

The adhesive backing material is applied to the back face of the primarybacking material to affix the yarn to the primary backing material.Typically, the adhesive backing material is applied by a pan applicatorusing a roller, a roll over a roller or a bed, or a knife (also called adoctor blade) over a roller or a bed. Properly applied adhesive backingmaterials do not substantially pass through the primary backingmaterial.

Most frequently, the adhesive backing material is applied as a singlecoating or layer. The extent or tenacity to which the yarn is affixed isreferred to as tuft lock or tuft bind strength. Carpets with sufficienttuft bind strength exhibit good wear resistance and, as such, have longservice lives. Also, the adhesive backing material should substantiallypenetrate the yarn (fiber bundle) exposed on the backside of the primarybacking material and should substantially consolidate individual fiberswithin the yarn. Good penetration of the yarn and consolidation offibers yields good abrasion resistance. Moreover, in addition to goodtuft bind strength and abrasion resistance, the adhesive material shouldalso impart or allow good flexibility to the carpet in order tofacilitate easy installation of the carpet.

The secondary backing material is typically a lightweight scrim made ofwoven or non-woven material such as a thermoplastic polymer, mostcommonly polypropylene. The secondary backing material is optionallyapplied to the backside of the carpet onto the adhesive backingmaterial, primarily to provide enhanced dimensional stability to thecarpet structure as well as to provide more surface area for theapplication of direct glue-down adhesives.

Alternative backing materials may also be applied to the backside of theadhesive backing material and/or to the backside of the secondarybacking material, if present. Alternative backing materials may includefoam cushioning (e.g. foamed polyurethane) and pressure sensitive flooradhesives. Alternative backing materials may also be applied, forexample, as webbing with enhanced surface area, to facilitate directglue-down adhesive installations (e.g., in contract commercialcarpeting, automobile carpet and airplane carpet where the need forcushioning is of times minimal). Alternative backing materials can alsobe optionally applied to enhance barrier protection respecting moisture,insects, and foodstuffs as well as to provide or enhance firesuppression, thermal insulation, and sound dampening properties of thecarpet.

Known adhesive backing materials include curable latex, urethane orvinyl systems, with latex systems being most common. Conventional latexsystems are low viscosity, aqueous compositions that are applied at highcarpet production rates and offer good fiber-to-backing adhesion, tuftbind strength and adequate flexibility. Generally, excess water isdriven off and the latex is cured by passing through a drying oven.Styrene butadiene rubbers (SBR) are the most common polymers used forlatex adhesive backing materials. Typically, the latex backing system isheavily filled with an inorganic filler such as calcium carbonate orAluminum Trihydrate and includes other ingredients such as antioxidants,antimicrobials, flame retardants, smoke suppressants, wetting agents,and froth aids.

Conventional latex adhesive backing systems can have certain drawbacks.As one important drawback, typical latex adhesive backing systems do notprovide a moisture barrier. Another possible drawback, particularly witha carpet having polypropylene yarn and polypropylene primary andsecondary backing materials, is the dissimilar polymer of latex systemsalong with the inorganic filler can reduce the recyclability of thecarpet.

In view of these drawbacks, some in the carpet industry have begunseeking suitable replacements for conventional latex adhesive backingsystems. One alternative is the use of urethane adhesive backingsystems. In addition to providing adequate adhesion to consolidate thecarpet, urethane backings generally exhibit good flexibility and barrierproperties and, when foamed, can eliminate the need for separateunderlayment padding (i.e., can constitute a direct glue-down unitarybacking system). However, urethane backing systems also have importantdrawbacks, including their relatively high cost and demanding curingrequirements which necessitate application at slow carpet productionrates relative to latex systems.

Thermoplastic polyolefins such as ethylene vinyl acetate (EVA)copolymers and low density polyethylene (LDPE) have also been suggestedas adhesive backing materials due in part to their low cost, goodmoisture stability and no-cure requirements. Various methods areavailable for applying polyolefin backing materials, including powdercoating, hot melt application and extruded film or sheet lamination.However, using polyolefins to replace latex adhesive backings can alsopresent difficulties. For example, U.S. Pat. No. 5,240,530, thedisclosure of which is incorporated herein by reference, at Table A,Col. 10, indicates that ordinary polyolefin resins possess inadequateadhesion for use in carpet construction. Additionally, relative to latexand other cured systems, ordinary polyolefins have relatively highapplication viscosities and relatively high thermal requirements. Thatis, ordinary thermoplastic polyolefins are characterized by relativelyhigh melt viscosities and high recrystallization or solidificationtemperatures relative to the typical aqueous viscosities and curetemperature requirements characteristic of latex and other cured(thermosetting) systems.

Even ordinary elastomeric polyolefins, i.e. polyolefins having lowcrystallinities, generally have relatively high viscosities andrelatively high recrystallization temperatures. High recrystallizationtemperatures result in relatively short molten times during processingand, combined with high melt viscosities can make it difficult toachieve adequate penetration of the yarn, especially at conventionaladhesive backing application rates.

One method for overcoming the viscosity and recrystallizationdeficiencies of ordinary polyolefins is to formulate the polyolefinresin as a hot melt adhesive which usually involves formulating lowmolecular weight polyolefins with waxes, tackifiers, various flowmodifiers and/or other elastomeric materials. Ethylene/vinyl acetate(EVA) copolymers, for example, have been used in formulated hot meltadhesive backing compositions and other polyolefins compositions havealso been proposed as hot melt backing compositions. For example, inU.S. Pat. No. 3,982,051, Taft et al., the disclosure of which isincorporated herein by reference, disclose that a composition comprisingan ethylene/vinyl acetate copolymer, atactic polypropylene andvulcanized rubber is useful as a hot melt carpet backing adhesive.

Unfortunately, hot melt adhesive systems are generally considered notcompletely suitable replacements for conventional latex adhesivebackings. Typical hot melt systems based on EVA and other copolymers ofethylene and unsaturated comonomers can require considerable formulatingand yet often yield inadequate tuft bind strengths. However, the mostsignificant deficiency of typical hot melt system is their meltstrengths which are generally too low to permit application by a directextrusion coating technique. As such, polyolefin hot melt systems aretypically applied to primary backings by relatively slow, less efficienttechniques such as by the use of heated doctor blades or rotating melttransfer rollers.

While unformulated high pressure low density polyethylene (LDPE) can beapplied by a conventional extrusion coating technique, LDPE resinstypically have poor flexibility which can result in excessive carpetstiffness. Conversely, those ordinary polyolefins that have improvedflexibility, such as ultra low density polyethylene (ULDPE) andethylene/propylene interpolymers, still do not possess sufficientflexibility, have excessively low melt strengths and/or tend to drawresonate during extrusion coating. To overcome extrusion coatingdifficulties, ordinary polyolefins with sufficient flexibility can beapplied by lamination techniques to insure adequate yarn-to-backingadhesion; however, lamination techniques are typically expensive and canresult in extended production rates relative to direct extrusion coatingtechniques.

Known examples of flexible polyolefin backing materials are disclosed inU.S. Pat. Nos. 3,390,035; 3,583,936; 3,745,054; and 3,914,489, thedisclosures of all of which are incorporated herein by reference. Ingeneral, these disclosures describe hot melt adhesive backingcompositions based on an ethylene copolymer, such as, ethylene/vinylacetate (EVA), and waxes. Known techniques for enhancing the penetrationof hot melt adhesive backing compositions through the yarn includeapplying pressure while the greige good is in contact with rotating melttransfer rollers as described, for example, in U.S. Pat. No. 3,551,231,the disclosure of which is incorporated herein by reference.

Another known technique for enhancing the effectiveness of hot meltsystems involve using pre-coat systems. For example, U.S. Pat. Nos.3,684,600; 3,583,936; and 3,745,054, the disclosures of all of which areincorporated herein by reference, describe the application of lowviscosity aqueous pre-coats to the back surface of the primary backingmaterial prior the application of a hot melt adhesive composition. Thehot melt adhesive backing systems disclosed in these patents are derivedfrom multi-component formulations based on functional ethylene polymerssuch as, for example, ethylene/ethyl acrylate (EEA) and ethylene/vinylacetate (EVA) copolymers.

Although there are various systems known in the art of carpet backings,there remains a need for a thermoplastic polyolefin carpet backingsystem which provides adequate tuft bind strength, good abrasionresistance and good flexibility to replace cured latex backing systems.A need also remains for an application method which permits high carpetproduction rates while achieving the desired characteristics of goodtuft bind strength, abrasion resistance, barrier properties andflexibility. Finally, there is also a need to provide a carpet structurehaving fibers and backing materials that are easily recyclable withoutthe necessity of extensive handling and segregation of carpet componentmaterials.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a carpetcomprises a plurality of fibers, a primary backing material having aface and a back side, an adhesive backing material and an optionalsecondary backing material, the plurality of fibers attached to theprimary backing material and protruding from the face of the primarybacking material and exposed on the back side of the primary backingmaterial, the adhesive backing material disposed on the back side of theprimary backing material and the optional secondary backing materialadjacent to the adhesive backing material, wherein at least one of theplurality of fibers, the primary backing material, the adhesive backingmaterial or the optional secondary backing material is comprised of atleast one homogeneously branched ethylene polymer characterized ashaving a short chain branching distribution index (SCBDI) of greaterthan or equal to 50 percent.

Another aspect of the present invention is a method of making a carpet,the carpet including a plurality of fibers, a primary backing materialhaving a face and a back side, an adhesive backing material and anoptional secondary backing material, the plurality of fibers attached tothe primary backing material and protruding from the face of the primarybacking material and exposed on the back side of the primary backingmaterial, the method comprising the step of extrusion coating theadhesive backing material or the optional secondary backing materialonto the back side of the primary backing material, wherein theextrusion coated adhesive backing material or optional secondary backingmaterial is comprised of at least one homogeneously branched ethylenepolymer characterized as having a short chain branching distributionindex (SCBDI) of greater than or equal to 50 percent.

Another aspect of the present invention is a method of making a carpet,the carpet having a collapsed, non-expanded adhesive backing materialmatrix and comprising yarn attached to a primary backing material, theadhesive backing material comprising at least one ethylene polymer andis in intimate contact with the primary backing material and hassubstantially penetrated and substantially consolidated the yarn, themethod comprising the step of adding an effective amount of at least oneimplosion agent to the adhesive backing material and thereafteractivating the implosion agent during an extrusion coating step suchthat molten or semi-molten polymer is forced into the free space of yarnexposed on the backside of the primary backing material.

Another aspect of the present invention is a method of making a carpet,the carpet having a face surface and comprising yarn, a primary backingmaterial, an adhesive backing material and an optional secondary backingmaterial, wherein the primary backing material has a back surfaceopposite the face surface of the carpet, the yarn is attached to theprimary backing material, the adhesive backing material is applied tothe back surface of the primary backing material and the optionalsecondary backing material is applied onto the adhesive backingmaterial, the method comprising the step of scouring, washing orflashing the back surface of the primary backing material with steam,solvent and/or heat prior to the application of the adhesive backingmaterial to substantially remove or displace processing materials.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an illustration of a tufted carpet 10.

FIG. 2 is a schematic representation of an extrusion coating line 20 formaking a carpet 70.

FIG. 3 consists of scanning electron microscopy photomicrographs at 20×magnification (3 a) and 50× magnification (3 b) illustrating theinterfaces of the various carpet components of Example 14.

FIG. 4 consists of scanning electron microscopy photomicrographs at 20×magnification (4 a) and 50× magnification (4 b) illustrating theinterfaces of the various carpet components of Example 22.

FIG. 5 is a X-Y plot of the effect of fiber bundle penetration by theadhesive backing material on the abrasion resistance performance ofpolypropylene and nylon carpet samples.

FIG. 6 is a cross-section showing the construction of a carpet tile inaccordance with the present invention.

FIG. 7 is a schematic representation of an extrusion coating line formaking carpet tile according to the present invention.

DEFINITION OF TERMS

The terms “intimate contact,” “substantial encapsulation,” and/or“substantial consolidation” are used herein to refer to mechanicaladhesion or mechanical interactions (as opposed to chemical bonding)between dissimilar carpet components, irrespective of whether or not oneor more carpet component is capable of chemically interacting withanother carpet component. With respect to the mechanical adhesion orinteractions of the present invention, there may be some effectiveamount of intermixing or inter-melting of polymeric materials; however,there is no continuous or integral fusing of various components asdetermined from visual inspection of photomicrographs (at 20×magnification) of the various carpet interfaces. Within this meaning,fusion of yarn or fiber bundles or of individual fibers to one anotherwithin a fiber bundle is not considered integral fusion in itself sincefibers are referred to herein as one carpet component.

The term “intimate contact” refers to the mechanical interaction betweenthe back surface of the primary backing material and the adhesivebacking material. The term “substantial encapsulation” refers to theadhesive backing material significantly surrounding the yarn or fiberbundles at or in immediate proximity to the interface between the backsurface of the primary backing material and the adhesive backingmaterial. The term “substantial consolidation” refers to the overallintegrity and dimensional stability of the carpet that is achieved bysubstantially encapsulating the yarn or fiber bundles and intimatelycontacting the back surface of the primary backing material with theadhesive backing material. A substantially consolidated carpet possessesgood component cohesiveness and good delamination resistance withrespect to the various carpet components.

The term “integral fusing” is used herein in the same sense as known inthe art and refers to heat bonding of carpet components using atemperature above the melting point of the adhesive backing material.Integral fusing occurs when the adhesive backing material comprises thesame polymer as either the fibers or primary backing material or both.However, integral fusing does not occur when the adhesive backingmaterial comprises a different polymer than the fibers and primarybacking material. By the term “same polymer,” it is meant that themonomer units of the polymers are of the same chemistry, although theirmolecular or morphological attributes may differ. Conversely, by theterm “different polymer,” it is meant that, irrespective of anymolecular or morphological differences, the monomer units of thepolymers are of different chemistries. Thus, in accordance with thevarious definitions of the present invention, a polypropylene primarybacking material and a polyethylene adhesive backing material would notintegrally fuse because these carpet components are of differentchemistries.

The term “carpet component” is used herein to refer separately to carpetfiber bundles, the primary backing material, the adhesive backingmaterial and the optional secondary backing material.

The term “extrusion coating” is used herein in its conventional sense torefer to an extrusion technique wherein a polymer composition usually inpellet-form is heated in an extruder to a temperature elevated above itsmelt temperature and then forced through a slot die to form asemi-molten or molten polymer web. The semi-molten or molten polymer webis continuously drawn down onto a continuously fed greige good to coatthe backside of the greige good with the polymer composition. FIG. 2illustrates an extrusion process of the present invention wherein, atthe nip, the face surface of the greige good is oriented towards thechill roll and the back surface of the adhesive backing materialoriented is towards the nip pressure roll. Extrusion coating is distinctfrom a lamination technique.

The term “lamination technique” is used herein in its conventional senserefer to applying adhesive backing materials to greige goods by firstforming the adhesive backing material as a solidified or substantiallysolidified film or sheet and thereafter, in a separate processing step,reheating or elevating the temperature of the film or sheet beforeapplying it to the back surface of the primary backing material.

The term “heat content” is used herein to refer to the mathematicalproduct of the heat capacity and specific gravity of a filler. Fillerscharacterized as having high heat content are used in specificembodiments of the present invention to extend the solidification ormolten time of adhesive backing materials. The Handbook for ChemicalTechnicians, Howard J. Strauss and Milton Kaufmann, McGraw Hill BookCompany, 1976, Sections 1-4 and 2-1, the disclosure of which isincorporated herein by reference, provides information on the heatcapacity and specific gravity of select mineral fillers. The fillerssuitable for use in the present invention do not change their physicalstate (i.e., remain a solid material) over the extrusion coatingprocessing temperature ranges of the present invention. Preferred highheat content fillers possess a combination of a high specific gravityand a high heat capacity.

The term “implosion agent” is used herein to refer to the use ofconventional blowing agents or other compounds which out-gas or causeout-gassing when activated by heat, usually at some particularactivation temperature. In the present invention, implosion agents areused to implode or force adhesive backing material into the free spaceof yarn or fiber bundles.

The term “processing material” is used herein to refer to substancessuch as spin finishing waxes, equipment oils, sizing agents and thelike, which can interfere with the adhesive or physical interfacialinteractions of adhesive backing materials. Processing materials can beremoved or displaced by a scouring or washing technique of the presentinvention whereby improved mechanical bonding is accomplished.

The terms “polypropylene carpet” and “polypropylene greige goods” areused herein to mean a carpet or greige goods substantially comprised ofpolypropylene fibers, irrespective of whether the primary backingmaterial for the carpet or greige good is comprised of polypropylene orsome other material.

The terms “nylon carpet” and “nylon greige goods” are used herein tomean a carpet or greige goods substantially comprised of nylon fibers,irrespective of whether the primary backing material for the carpet orgreige good is comprised of nylon or some other material.

The term “linear” as used to describe ethylene polymers is used hereinto mean the polymer backbone of the ethylene polymer lacks measurable ordemonstrable long chain branches, e.g., the polymer is substituted withan average of less than 0.01 long branch/1000 carbons.

The term “homogeneous ethylene polymer” as used to describe ethylenepolymers is used in the conventional sense in accordance with theoriginal disclosure by Elston in U.S. Pat. No. 3,645,992, the disclosureof which is incorporated herein by reference, to refer to an ethylenepolymer in which the comonomer is randomly distributed within a givenpolymer molecule and wherein substantially all of the polymer moleculeshave substantially the same ethylene to comonomer molar ratio. Asdefined herein, both substantially linear ethylene polymers andhomogeneously branched linear ethylene are homogeneous ethylenepolymers.

Homogeneously branched ethylene polymers are homogeneous ethylenepolymers that possess short chain branches and that are characterized bya relatively high short chain branching distribution index (SCBDI) orrelatively high composition distribution branching index (CDBI). Thatis, the ethylene polymer has a SCBDI or CDBI greater than or equal to 50percent, preferably greater than or equal to 70 percent, more preferablygreater than or equal to 90 percent and essentially lack a measurablehigh density (crystalline) polymer fraction.

The SCBDI or CDBI is defined as the weight percent of the polymermolecules having a comonomer content within 50 percent of the mediantotal molar comonomer content and represents a comparison of thecomonomer distribution in the polymer to the comonomer distributionexpected for a Bernoullian distribution. The SCBDI or CDBI ofpolyolefins can be conveniently calculated from data obtained fromtechniques known in the art, such as, for example, temperature risingelution fractionation (abbreviated herein as “TREF”) as described, forexample, by Wild et al., Journal of Polymer Science, Poly. Phys. Ed.,Vol. 20, p. 441 (1982), L. D. Cady, “The Role of Comonomer Type andDistribution in LLDPE Product Performance,” SPE Regional TechnicalConference, Quaker Square Hilton, Akron, Ohio, October 1-2, pp. 107-119(1985), or in U.S. Pat. Nos. 4,798,081 and 5,008,204, the disclosures ofall of which are incorporated herein by reference. However, thepreferred TREF technique does not include purge quantities in SCBDI orCDBI calculations. More preferably, the comonomer distribution of thepolymer and SCBDI or CDBI are determined using ¹³C NMR analysis inaccordance with techniques described, for example, in U.S. Pat. No.5,292,845 and by J. C. Randall in Rev. Macromol. Chem. Phys., C29, pp.201-317, the disclosures of which are incorporated herein by reference.

The terms “homogeneously branched linear ethylene polymer” and“homogeneously branched linear ethylene/α-olefin polymer” means that theolefin polymer has a homogeneous or narrow short branching distribution(i.e., the polymer has a relatively high SCBDI or CDBI) but does nothave long chain branching. That is, the linear ethylene polymer is ahomogeneous ethylene polymer characterized by an absence of long chainbranching. Such polymers can be made using polymerization processes(e.g., as described by Elston in U.S. Pat. No. 3,645,992) which providea uniform short chain branching distribution (i.e., homogeneouslybranched). In his polymerization process, Elston uses soluble vanadiumcatalyst systems to make such polymers, however others, such as MitsuiPetrochemical Industries and Exxon Chemical Company, have reportedlyused so-called single site catalyst systems to make polymers having ahomogeneous structure similar to polymer described by Elston. U.S. Pat.No. 4,937,299 to Ewen et al. and U.S. Pat. No. 5,218,071 to Tsutsui etal., the disclosures of which are incorporated herein by reference,disclose the use of metallocene catalysts, such as catalyst systemsbased on hafnium, for the preparation of homogeneously branched linearethylene polymers. Homogeneously branched linear ethylene polymers aretypically characterized as having a molecular weight distribution,M_(w)/M_(n), of less than 3, preferably less than 2.8, more preferablyless than 2.3. Commercial examples of suitable homogeneously branchedlinear ethylene polymers include those sold by Mitsui PetrochemicalIndustries as Tafmer™ resins and by Exxon Chemical Company as Exact™resins and Exceed™ resins.

The terms “homogeneous linearly branched ethylene polymer” or“homogeneously branched linear ethylene/α-olefin polymer” do not referto high pressure branched polyethylene which is known to those skilledin the art to have numerous long chain branches. The term “homogeneouslinear ethylene polymer” generically refers to both linear ethylenehomopolymers and to linear ethylene/α-olefin interpolymers. A linearethylene/α-olefin interpolymer possesses short chain branching and n theα-olefin is typically at least one C₃-C₂₀ α-olefin (e.g., propylene,1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, and 1-octene).

When used in reference to an ethylene homopolymer (i.e., a high densityethylene polymer not containing any comonomer and thus no short chainbranches), the term “homogeneous ethylene polymer” or “homogeneouslinear ethylene polymer” means the polymer was made using a homogeneouscatalyst system such as, for example, that described Elston or Ewen orthose described by Canich in U.S. Pat. Nos. 5,026,798 and 5,055,438, orby Stevens et al. in U.S. Pat. No. 5,064,802, the disclosures of allthree of which are incorporated herein by reference.

The term “substantially linear ethylene polymer” is used herein to referspecially to homogeneously branched ethylene polymers that have longchain branching. The term does not refer to heterogeneously orhomogeneously branched ethylene polymers that have a linear polymerbackbone. For substantially linear ethylene polymers, the long chainbranches have the same comonomer distribution as the polymer backbone,and the long chain branches can be as long as about the same length asthe length of the polymer backbone to which they are attached. Thepolymer backbone of substantially linear ethylene polymers issubstituted with about 0.01 long chain branches/1000 carbons to about 3long chain branches/1000 carbons, more preferably from about 0.01 longchain branches/1000 carbons to about 1 long chain branches/1000 carbons,and especially from about 0.05 long chain branches/1000 carbons to about1 long chain branches/1000 carbons.

Long chain branching is defined herein as a chain length of at least 6carbons, above which the length cannot be distinguished using ¹³Cnuclear magnetic resonance spectroscopy. The presence of long chainbranching can be determined in ethylene homopolymers by using ¹³Cnuclear magnetic resonance (NMR) spectroscopy and is quantified usingthe method described by Randall (Rev. Macromol. Chem. Phys., C29, V.2&3, p. 285-297), the disclosure of which is incorporated herein byreference.

Although current ¹³C nuclear magnetic resonance spectroscopy cannotdetermine the length of a long chain branch in excess of six carbonatoms, there are other known techniques useful for determining thepresence of long chain branches in ethylene polymers, includingethylene/1-octene interpolymers. Two such methods are gel permeationchromatography coupled with a low angle laser light scattering detector(GPC-LALLS) and gel permeation chromatography coupled with adifferential viscometer detector (GPC-DV). The use of these techniquesfor long chain branch detection and the underlying theories have beenwell documented in the literature. See, e.g., Zimm, G. H. andStockmayer, W. H., J. Chem. Phys., 17, 1301 (1949) and Rudin, A., ModernMethods of Polymer Characterization, John Wiley & Sons, New York (1991)pp. 103-112, the disclosures of which are incorporated herein byreference.

A. Willem deGroot and P. Steve Chum, both of The Dow Chemical Company,at the Oct. 4, 1994 conference of the Federation of Analytical Chemistryand Spectroscopy Society (FACSS) in St. Louis, Mo., presented datademonstrating that GPC-DV is a useful technique for quantifying thepresence of long chain branches in substantially linear ethylenepolymers. In particular, deGroot and Chum found that the level of longchain branches in substantially linear ethylene homopolymer samplesmeasured using the Zimm-Stockmayer equation correlated well with thelevel of long chain branches measured using ¹³C NMR.

Further, deGroot and Chum found that the presence of octene does notchange the hydrodynamic volume of the polyethylene samples in solutionand, as such, one can account for the molecular weight increaseattributable to octene short chain branches by knowing the mole percentoctene in the sample. By deconvoluting the contribution to molecularweight increase attributable to 1-octene short chain branches, deGrootand Chum showed that GPC-DV may be used to quantify the level of longchain branches in substantially linear ethylene/octene copolymers.

DeGroot and Chum also showed that a plot of Log(I₂, melt index) as afunction of Log(GPC Weight Average Molecular Weight) as determined byGPC-DV illustrates that the long chain branching aspects (but not theextent of long branching) of substantially linear ethylene polymers arecomparable to that of high pressure, highly branched low densitypolyethylene (LDPE) and are clearly distinct from ethylene polymersproduced using Ziegler-type catalysts such as titanium complexes andordinary homogeneous catalysts such as hafnium and vanadium complexes.

For substantially linear ethylene polymers, the long chain branch islonger than the short chain branch that results from the incorporationof the α-olefin(s) into the polymer backbone. The empirical effect ofthe presence of long chain branching in the substantially linearethylene polymers used in the invention is manifested as enhancedrheological properties which are quantified and expressed herein interms of gas extrusion rheometry (GER) results and/or melt flow, I₁₀/I₂,increases.

Substantially linear ethylene polymers are homogeneously branchedethylene polymers and are disclosed in U.S. Pat. No. 5,272,236 and U.S.Pat. No. 5,278,272, the disclosures of which are incorporated herein byreference. Homogeneously branched substantially linear ethylene polymersare available from The Dow Chemical Company as AFFINITY™ polyolefinplastomers and from Dupont Dow Elastomers JV as ENGAGE™ polyolefinelastomers. Homogeneously branched substantially linear ethylenepolymers can be prepared via the solution, slurry, or gas phasepolymerization of ethylene and one or more optional α-olefin comonomersin the presence of a constrained geometry catalyst, such as the methoddisclosed in European Patent Application 416,815-A, the disclosure ofwhich is incorporated herein by reference. Preferably, a solutionpolymerization process is used to manufacture the substantially linearethylene polymer used in the present invention.

The terms “heterogeneous” and “heterogeneously branched” mean that theethylene polymer is characterized as a mixture of interpolymer moleculeshaving various ethylene to comonomer molar ratios. Heterogeneouslybranched ethylene polymers are characterized as having a short chainbranching distribution index (SCBDI) less than about 30 percent.Heterogeneously branched linear ethylene polymers are available from TheDow Chemical Company as DOWLEX™ linear low density polyethylene and asATTANE™ ultra-low density polyethylene resins. Heterogeneously branchedlinear ethylene polymers can be prepared via the solution, slurry or gasphase polymerization of ethylene and one or more optional alpha-olefincomonomers in the presence of a Ziegler Natta catalyst, by processessuch as are disclosed in U.S. Pat. No. 4,076,698 to Anderson et al., thedisclosure of which is incorporated herein by reference. Heterogeneouslybranched ethylene polymers are typically characterized as havingmolecular weight distributions, M_(w)/M_(n), in the range of from 3.5 to4.1 and, as such, are distinct from substantially linear ethylenepolymers and homogeneously branched linear ethylene polymers in regardsto both compositional short chain branching distribution and molecularweight distribution.

The substantially linear ethylene polymers used in the present inventionare not in the same class as homogeneously branched linear ethylenepolymers, nor heterogeneously branched linear ethylene polymers, nor aresubstantially linear ethylene polymers in the same class as traditionalhighly branched low density polyethylene (LDPE). The substantiallylinear ethylene polymers useful in this invention surprisingly haveexcellent processability, even though they have relatively narrowmolecular weight distributions (MWDs). Even more surprising, the meltflow ratio (I₁₀/I₂) of the substantially linear ethylene polymers can bevaried essentially independently of the polydispersity index (i.e.,molecular weight distribution (M_(w)/M_(n))). This is contrasted withconventional heterogeneously branched linear polyethylene resins whichhave rheological properties such that as the polydispersity indexincreases, the I₁₀/I₂ value also increases. The rheological propertiesof substantially linear ethylene polymers also differ from homogeneouslybranched linear ethylene polymers which have relatively low, essentiallyfixed I₁₀/I₂ ratios.

DETAILED DESCRIPTION OF THE INVENTION

The Preferred Polymers

We have discovered that substantially linear ethylene polymers andhomogeneously branched linear ethylene polymers (i.e., homogeneouslybranched ethylene polymers) offer unique advantages for extrusion coatedcarpet backing applications, especially for commercial and residentialcarpet markets. Homogeneously branched ethylene polymers (includingsubstantially linear ethylene polymers in particular) have lowsolidification temperatures, good adhesion to polypropylene, and lowmodulus relative to conventional ethylene polymers such as low densitypolyethylene (LDPE), heterogeneously branched linear low densitypolyethylene (LLDPE), high density polyethylene (HDPE), andheterogeneously branched ultra low density polyethylene (ULDPE). Assuch, homogeneously branched ethylene polymers are useful for makingcarpet fibers, primary backing materials, adhesive backing materials andoptional secondary backing materials. However, homogeneously branchedethylene polymers are particularly useful as adhesive backing materialsfor tufted carpet and non-tufted carpet (e.g., needle-punched carpet)and are especially useful for tufted carpets.

In the present invention, during extrusion coating of the backside ofcarpet to apply an adhesive backing material, properly selectedsubstantially linear ethylene polymers and homogeneously branched linearethylene polymers show good penetration of carpet yarns (fiber bundles)and also allow good consolidation of the fibers within the yarn. Whenused for tufted carpets, the tuft bind strength and abrasion resistanceof the carpet is increased by the penetration of substantially linearethylene polymers and homogeneously branched linear ethylene polymersinto the yarn. Preferably, a tuft bind (or tuft lock) strength of 3.25pounds (1.5 kg) or more is achieved, more preferably 5 pounds (2.3 kg)or more and most preferably 7.5 pounds (3.4 kg) or more. In addition toimproved penetration of the yarn, tuft bind strength can be also beincreased by increasing the molecular weight of the polymer. However, ahigher polymer molecular weight selected for improved tuft bind strengthis contra to the requirement of a lower polymer molecular weight whichis generally needed for good yarn penetration and good extrusioncoatability. Also, higher polymer densities are desirable for improvedchemical and barrier resistance, yet higher densities invariably yieldstiffer carpets. As such, polymer properties must be chosen such that abalance is maintained between extrusion coatability and abrasionresistance as well as between chemical resistance and carpetflexibility.

When carpet greige goods are backed with properly selected substantiallylinear ethylene polymers or homogeneously branched linear ethylenepolymers, the low flexural modulus of these polymers offers advantagesin ease of carpet installation and general carpet handling.Substantially linear ethylene polymers, in particular, when employed asan adhesive backing material show enhanced mechanical adhesion topolypropylene which improves the consolidation and delaminationresistance of the various carpet layers and components, i.e.,polypropylene fibers, fiber bundles, the primary backing material, theadhesive backing material and the secondary backing material whenoptionally applied. Consequently, exceptionally good abrasion resistanceand tuft bind strength can be obtained. Good abrasion resistance isespecially important in commercial carpet cleaning operations as goodabrasion resistance generally improves carpet durability.

Properly selected substantially linear ethylene polymers can allow theelimination of secondary backing materials and as such can result insignificant manufacturing cost savings. In addition, carpets adhesivelybacked with a substantially linear ethylene polymer or homogeneouslybranched linear ethylene polymer can provide a substantial fluid andparticle barrier which enhances the hygienic properties of carpet.

A substantially linear ethylene polymer or homogeneously branched linearethylene polymer adhesive backing material can allow totally recyclablecarpet products particularly where the carpet comprises polypropylenefibers. In addition, the mixture of a substantially linear ethylenepolymer or a homogeneously branched linear ethylene polymer with afiber-grade polypropylene resin can result in an impact modified recyclecomposition which is useful for injection molding and other moldingapplications as well as reuse in carpet construction, for example, asthe primary backing material or as a blend component of the adhesivebacking material polymer composition. That is, polyolefin polymermixtures can involve sufficiently similar polymer chemistries,compatibilities, and/or miscibilities to permit good recyclabilitywithout having sufficient similarities to permit integral fusion.

The preferred homogeneously branched ethylene polymer has a singlemelting peak between −30° C. and 150° C., as determined usingdifferential scanning calorimetry. The most preferred homogeneouslybranched ethylene polymer for use in the invention is a substantiallylinear ethylene polymer characterized as having

-   -   (a) a melt flow ratio, I₁₀/I₂≧5.63,    -   (b) a molecular weight distribution, M_(w)/M_(n), as determined        by gel permeation chromatography and defined by the equation:        (M _(w) /M _(n))≦(I ₀ /I ₂)−4.63,    -   (c) a gas extrusion rheology such that the critical shear rate        at onset of surface melt fracture for the substantially linear        ethylene polymer is at least 50 percent greater than the        critical shear rate at the onset of surface melt fracture for a        linear ethylene polymer, wherein the linear ethylene polymer has        a homogeneously branched short chain branching distribution and        no long chain branching, and wherein the substantially linear        ethylene polymer and the linear ethylene polymer are        simultaneously ethylene homopolymers or interpolymers of        ethylene and at least one C₃-C₂₀ α-olefin and have the same I₂        and M_(w)/M_(n) and wherein the respective critical shear rates        of the substantially linear ethylene polymer and the linear        ethylene polymer are measured at the same melt temperature using        a gas extrusion rheometer.    -   (d) a single differential scanning calorimetry, DSC, melting        peak between −30° and 150° C.

Determination of the critical shear rate in regards to melt fracture aswell as other rheology properties such as “rheological processing index”(PI), is performed using a gas extrusion rheometer (GER). The gasextrusion rheometer is described by M. Shida, R. N. Shroff and L. V.Cancio in Polymer Engineering Science, Vol. 17, No. 11, p. 770 (1977),and in “Rheometers for Molten Plastics” by John Dealy, published by VanNostrand Reinhold Co. (1982) on pp. 97-99, the disclosures of both ofwhich are incorporated herein by reference. GER experiments areperformed at a temperature of 190° C., at nitrogen pressures betweenabout 250 and about 5500 psig (about 1.7 and about 37.4 MPa) using a0.0754 mm diameter, 20:1 L/D die with an entrance angle of about 180°.For the substantially linear ethylene polymers used herein, the PI isthe apparent viscosity (in kpoise) of a material measured by GER at anapparent shear stress of 2.15×10⁶ dyne/^(cm2) (2.19×10⁴ kg/m²). Thesubstantially linear ethylene polymer for use in the invention have a PIin the range of 0.01 kpoise to 50 kpoise, preferably 15 kpoise or less.The substantially linear ethylene polymers used herein also have a PIless than or equal to 70 percent of the PI of a linear ethylene polymer(either a Ziegler polymerized polymer or a homogeneously branched linearpolymer as described by Elston in U.S. Pat. No. 3,645,992) having an I₂and M_(w)/M_(n), each within ten percent of the substantially linearethylene polymer.

An apparent shear stress versus apparent shear rate plot is used toidentify the melt fracture phenomena and quantify the critical shearrate and critical shear stress of ethylene polymers. According toRamamurthy in the Journal of Rheology, 30(2), 337-357, 1986, thedisclosure of which is incorporated herein by reference, above a certaincritical flow rate, the observed extrudate irregularities may be broadlyclassified into two main types: surface melt fracture and gross meltfracture.

Surface melt fracture occurs under apparently steady flow conditions andranges in detail from loss of specular film gloss to the more severeform of “sharkskin.” Herein, as determined using the above-describedGER, the onset of surface melt fracture (OSMF) is characterized at thebeginning of losing extrudate gloss at which the surface roughness ofthe extrudate can only be detected by 40× magnification. As described inU.S. Pat. No. 5,278,272, the critical shear rate at the onset of surfacemelt fracture for the substantially linear ethylene interpolymers andhomopolymers is at least 50 percent greater than the critical shear rateat the onset of surface melt fracture of a linear ethylene polymerhaving essentially the same I₂ and M_(w)/M_(n).

Gross melt fracture occurs at unsteady extrusion flow conditions andranges in detail from regular (alternating rough and smooth, helical,etc.) to random distortions. For commercial acceptability to maximizethe performance properties of films, coatings and moldings, surfacedefects should be minimal, if not absent. The critical shear stress atthe onset of gross melt fracture for the substantially linear ethylenepolymers used in the invention, especially those having a density >0.910g/cc, is greater than 4×10⁶ dynes/cm². The critical shear rate at theonset of surface melt fracture (OSMF) and the onset of gross meltfracture (OGMF) will be used herein based on the changes of surfaceroughness and configurations of the extrudates extruded by a GER.

The homogeneously branched ethylene polymers used in the presentinvention are characterized by a single DSC melting peak. The singlemelting peak is determined using a differential scanning calorimeterstandardized with indium and deionized water. The method involves 5-7 mgsample sizes, a “first heat” to about 140° C. which is held for 4minutes, a cool down at 10°/min. to −30° C. which is held for 3 minutes,and heat up at 10° C./min. to 150° C. for the “second heat”. The singlemelting peak is taken from the “second heat” heat flow vs. temperaturecurve. Total heat of fusion of the polymer is calculated from the areaunder the curve.

For polymers having a density of 0.875 g/cc to 0.910 g/cc, the singlemelting peak may show, depending on equipment sensitivity, a “shoulder”or a “hump” on the low melting side that constitutes less than 12percent, typically, less than 9 percent, and more typically less than 6percent of the total heat of fusion of the polymer. Such an artifact isobservable for other homogeneously branched polymers such as Exact™resins and is discerned on the basis of the slope of the single meltingpeak varying monotonically through the melting region of the artifact.Such an artifact occurs within 34° C., typically within 27° C., and moretypically within 20° C. of the melting point of the single melting peak.The heat of fusion attributable to an artifact can be separatelydetermined by specific integration of its associated area under the heatflow vs. temperature curve.

Whole polymer product samples and individual polymer components areanalyzed by gel permeation chromatography (GPC) on a Waters 150 hightemperature chromatographic unit equipped with three mixed porositycolumns (Polymer Laboratories 10³, 10⁴, 10⁵ and 10⁶ Å), operating at asystem temperature of 140° C. The solvent is 1,2,4-trichlorobenzene,from which 0.3 percent by weight solutions of the samples are preparedfor injection. The flow rate is 1.0 milliliters/minute and the injectionsize is 100 microliters.

The molecular weight determination with is deduced by using narrowmolecular weight distribution polystyrene standards (from PolymerLaboratories) in conjunction with their elution volumes. The equivalentpolyethylene molecular weights are determined by using appropriateMark-Houwink coefficients for polyethylene and polystyrene (as describedby Williams and Ward in Journal of Polymer Science, Polymer Letters,Vol. 6, p. 621, 1968, the disclosure of which is incorporated herein byreference) to derive the following equation:M _(polyethylene) =a*(M _(polystyrene))^(b).

In this equation, a=0.4316 and b=1.0. Weight average molecular weight,M_(w), and number average molecular weight, M_(n), are calculated in theusual manner according to the following formula: M_(j)=(S w_(i)(M_(i)^(j)))^(j); where w_(i) is the weight fraction of the molecules withM_(i) eluting from the GPC column in fraction i and j=1 when calculatingM_(w) and j=−1 when calculating M_(n).

The molecular weight distribution (M_(w)/M_(n)) for the substantiallylinear ethylene polymers and homogeneous linear ethylene polymers usedin the present invention is generally from about 1.8 to about 2.8.

However, substantially linear ethylene polymers are known to haveexcellent processability, despite having a relatively narrow molecularweight distribution. Unlike homogeneously and heterogeneously branchedlinear ethylene polymers, the melt flow ratio (I₁₀/I₂) of substantiallylinear ethylene polymers can be varied essentially independently oftheir molecular weight distribution, M_(w)/M_(n).

Suitable homogeneously branched ethylene polymers for use in the presentinvention include interpolymers of ethylene and at least one α-olefinprepared by a solution, gas phase or slurry polymerization process orcombinations thereof. Suitable α-olefins are represented by thefollowing formula:CH₂═CHRwhere R is a hydrocarbyl radical. Further, R may be a hydrocarbylradical having from one to twenty carbon atoms and as such the formulaincludes C₃-C₂₀ α-olefins. Suitable α-olefins for use as comonomersinclude propylene, 1-butene, 1-isobutylene, 1-pentene, 1-hexene,4-methyl-1-pentene, 1-heptene and 1-octene, as well as other comonomertypes such as styrene, halo- or alkyl-substituted styrenes,tetrafluoro-ethylene, vinyl benzocyclobutane, 1,4-hexadiene,1,7-octadiene, and cycloalkenes, e.g., cyclopentene, cyclohexene andcyclooctene. Preferably, the comonomer will be 1-butene, 1-pentene,4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, or mixtures thereof,as adhesive backing materials comprised of higher α-olefins will haveespecially improved toughness. However, most preferably, the comonomerwill be 1-octene and the ethylene polymer will be prepared in a solutionprocess.

The density of the substantially linear ethylene polymer orhomogeneously branched linear ethylene polymer, as measured inaccordance with ASTM D-792, does not exceed 0.92 g/cc, and is generallyin the range from about 0.85 g/cc to about 0.92 g/cc, preferably fromabout 0.86 g/cc to about 0.91 g/cc, and especially from about 0.86 g/ccto about 0.90 g/cc.

The molecular weight of the homogeneously branched linear ethylenepolymer or substantially linear ethylene polymer is convenientlyindicated using a melt index measurement according to ASTM D-1238,Condition 190° C./2.16 kg (formerly known as “Condition (E)” and alsoknown as I₂). Melt index is inversely proportional to the molecularweight of the polymer. Thus, the higher the molecular weight, the lowerthe melt index, although the relationship is not linear. The melt indexfor the homogeneously branched linear ethylene polymer or substantiallylinear ethylene polymer is generally from about 1 grams/10 minutes (g/10min) to about 500 g/10 min, preferably about 2 g/10 min. to about 300g/10 min., more preferably from about 5 g/10 min to about 100 g/10 min.,especially from about 10 g/10 min. to about 50 g/10 min., and mostespecially about 25 to about 35 g/10 min.

Another measurement useful in characterizing the molecular weight of thehomogeneous linear ethylene polymer or the substantially linear ethylenepolymer is conveniently indicated using a melt index measurementaccording to ASTM D-1238, Condition 190° C./10 kg (formerly known as“Condition (N)” and also known as I₁₀). The ratio of the I₁₀ and the I₂melt index terms is the melt flow ratio and is designated as I₁₀/I₂. Forthe substantially linear ethylene polymer, the I₁₀/I₂ ratio indicatesthe degree of long chain branching, i.e., the higher the I₁₀/I₂ ratio,the more long chain branching in the polymer. The I₁₀/I₂ ratio of thesubstantially linear ethylene polymer is at least 6.5, preferably atleast 7, especially at least 8. The I₁₀/I₂ ratio of the homogeneouslybranched linear ethylene polymer is generally less than 6.3.

Preferred ethylene polymers for us in the present invention have arelative low modulus. That is, the ethylene polymer is characterized ashaving a 2% secant modulus less than 24,000 psi (163.3 MPa), especiallyless than 19,000 psi (129.3 MPa) and most especially less than 14,000psi (95.2 MPa), as measured in accordance with ASTM D790.

Preferred ethylene polymers for use in the a present invention aresubstantially amorphous or totally amorphous. That is, the ethylenepolymer is characterized as having a percent crystallinity less than 40percent, preferably less than 30 percent, more preferably less than 20and most preferably less than 10 percent, as measured by differentialscanning calorimetry using the equation percentcrystallinity=H_(f)/292*100, where H_(f) is the heat of fusion inJoules/gram.

The homogeneously branched ethylene polymer can be used alone or can beblended or mixed with one or more synthetic or natural polymericmaterial. Suitable polymers for blending or mixing with homogeneouslybranched ethylene polymers used in the present invention include, butare not limited to, another homogeneously branched ethylene polymer, lowdensity polyethylene, heterogeneously branched LLDPE, heterogeneouslybranched ULDPE, medium density polyethylene, high density polyethylene,grafted polyethylene (e.g. a maleic anhydride extrusion graftedheterogeneously branched linear low polyethylene or a maleic anhydrideextrusion grafted homogeneously branched ultra low densitypolyethylene), ethylene acrylic acid copolymer, ethylene vinyl acetatecopolymer, ethylene ethyl acrylate copolymer, polystyrene,polypropylene, polyester, polyurethane, polybutylene, polyamide,polycarbonate, rubbers, ethylene propylene polymers, ethylene styrenepolymers, styrene block copolymers, and vulcanates.

The actual blending or mixing of various polymers may be convenientlyaccomplished by any technique known in the art including, but notlimited to, melt extrusion compounding, dry blending, roll milling, meltmixing such as in a Banbury mixer and multiple reactor polymerization.Preferred blends or mixtures include a homogeneously branched ethylenepolymer and a heterogeneously branched ethylene α-olefin interpolymerwherein the α-olefin is a C₃-C₈ α-olefin prepared using two reactorsoperated in parallel or in series with different catalyst systemsemployed in each reactor. Multiple reactor polymerizations are describedin copending applications U.S. Ser. No. 08/544,497, filed Oct. 18, 1995and U.S. Ser. No. 08/327,156, filed Oct. 21, 1994, the disclosures ofall three of which are incorporated herein by reference. However,preferred multiple reactor polymerizations comprise non-adiabaticsolution loop reactors as described in provisional applications U.S.Ser. No. 60/014,696 and U.S. Ser. No. 60/014,705, both filed Apr. 1,1996, the disclosures of all of which are incorporated herein byreference.

The Preferred Methods and Equipment

A range of resin properties, processing conditions and equipmentconfigurations have been discovered for extrusion coatable carpetbacking systems that deliver performance similar or better thanincumbent latex and polyurethane systems.

FIG. 1 is an illustration of a tufted carpet 10. The tufted carpet 10 ismade of a primary backing material 11 with yarn 12 tufted therethrough;an adhesive backing material 13 which is in intimate contact with theback surface of the primary backing material 11, substantiallyencapsulates the yarn 12 and penetrates the yarn 12 and binds individualcarpet fibers; and an optional secondary backing material 14 applied tothe back surface of the adhesive backing material 13.

FIG. 2 is an illustration of an extrusion coating line 20 for making acarpet 70. The line 20 includes an extruder 21 equipped with a slot die22, a nip roll 24, a chill roll 23, an exhaust hood 26, a greige goodfeeder roll 28 and a pre-heater 25. As illustrated, the nip roll ispreferably equipped with a vacuum slot 29 to draw a vacuum across about60 degrees or about 17 percent of its circumference and is equipped witha vacuum pump 27. The slot die 22 dispenses an adhesive backing materialin the form of a semi-molten or molten polymer web 30 onto greige good40 with the polymer web 30 towards the chill roll 23 and the greige good40 towards the optional vacuum nip roll 24. As illustrated, an optionalsecondary backing material 50 is applied onto the polymer web 30. Thepoint where the nip roll 24 and the chill roll 23 are closest to oneanother is referred to as the nip 60.

The present invention is useful in producing carpets with face yarn madefrom various materials including, but not limited to, polypropylene,nylon, wool, cotton, acrylic, polyester andpolytrimethylenetheraphthalate (PTT). However, again because one of theobjects of the present invention is to provide a recyclable carpet suchas, for example, a 100% polyolefin carpet, the most preferred yarncomprises a polyolefin, more preferably, polypropylene. Most preferably,the yarn used in the present invention is an air entangled 2750 denierpolypropylene yarn such as that produced by Shaw Industries, Inc. andsold under the designation “Permacolor 2750 Type 015.”

The preferred primary backing material comprises a polyolefin, morepreferably polypropylene. Most preferably, the primary backing materialis a slit film polypropylene sheet such as that sold by AMOCO orSynthetic Industries. Alternatively, other types of primary backingmaterials, such as non-woven webs, can also be used. Although othermaterials, such as polyesters or polyamides can be used for the primarybacking material, it is preferred to use a polyolefin so that theobjective of producing a carpet made entirely from polyolefins isachieved. In addition, polypropylene primary backing materials aretypically lower in cost.

The method of tufting or needle-punching the yarn is not deemed criticalto the present invention. Thus, any conventional tufting orneedle-punching apparatus and stitch patterns can be used. Likewise, itdoes not matter whether tufted yarn loops are left uncut to produce aloop pile; cut to make cut pile; or cut, partially cut and uncut to makea face texture known as tip sheared.

After the yarn is tufted or needle-punched into the primary backingmaterial, the greige good is typically rolled up with the back side ofthe primary backing material facing outward and held until it istransferred to the backing line.

In a preferred embodiment, the greige good is scoured or washed beforeit has an adhesive backing material extruded thereon. In particular,yarn that is tufted or needle-punched to make carpet often has varyingquantities of processing materials, most commonly oily or waxychemicals, known as spin-finish chemicals, remaining thereon from theyarn manufacturing processes. It has been found to be preferable toremove or displace all or substantially all of these processingmaterials prior to extruding the adhesive backing material onto the backsurface of the primary backing material. A preferred scouring or washingmethod includes passing the greige good through a bath containing anaqueous detergent solution at about 64 to about 70° C. (e.g., 67° C.).Suitable detergents include, but are not limited to, STA which isavailable from American Emulsions. After the detergent washingprocessing step, the greige good is dried or preheated. Drying can beaccomplished at a temperature of about 108° C. to about 112° C. (e.g.,110° C.) for about 1.8 to about 2.2 minutes (e.g., 2 minutes).

Another preferred scouring or washing method includes using a wet vacuumcleaner system that initially dispenses ambient temperature water orheated water (either optionally containing a detergent or cleaningsolution) onto the primary backing material side of the greige good andthen sequentially vacuums up the water and retained amounts ofprocessing materials. The wet vacuum system is suitably adapted with adispensing and vacuum wand or head such that the entire width of thegreige good can be wet vacuumed at least once on a continuous extrusioncoating line. After the wet vacuuming processing step, the greige goodis suitably dried and/or preheated. Suitable detergents, cleaningsolutions or cleaning concentrates for use in a wet vacuuming methodincludes, but is not limited to, aqueous alkaline solutions, forexample, those consisting of ethylene diamine tetracetic acidtetrasodium salt. One suitable wet vacuum cleaner system is theRinsevac™ carpet cleaning system and one suitable cleaning concentrateis the Rinsevac™ Professional Carpet Cleaner both supplied by BlueLustre Products, Inc., Indianapolis, In.

Other suitable methods of the present invention for scouring or washingprocessing materials, adaptable to an extrusion coating line such as,for example, the one illustrated in FIG. 2, include steam cleaning,flashing at elevated temperatures and/or under vacuum, and solventchemical washing of the greige good.

It is also contemplated that the use of polyolefin waxes (rather thanconventional organic and mineral oils) as processing materials wouldallow improved adhesive backing material performance in itself or atleast less demanding scouring or washing requirements. Nevertheless,practitioners will find that scouring or washing requirements may varywith the amount and specific type of processing materials present. Thatis, higher quantities of process materials and/or higher molecularprocessing materials may require more stringent scouring and washingtechniques such as, for example, multiple washing and drying steps usingconcentrated washing solutions based on softened or deionized water.Practitioners will also recognize that scouring and washing requirementsfor effectively removing or displacing processing materials may be moreextensive than ordinary washings or other cleaning procedures performedfor cosmetic or decorative purposes or performed to simply remove loosefibers, primary backing material or other debris that ordinarily resultfrom tufting, needle-punch and/or cutting operations.

In another aspect of the present invention, the greige good is coatedwith an aqueous pre-coat material, either as a final backing orpreferably before an adhesive backing material is extruded thereon. Theparticles in this dispersion can be made from various polyolefinmaterials such as ethylene acrylic acid (EAA), ethylene vinyl acetate(EVA), polypropylene or polyethylene (e.g., low density polyethylene(LDPE), linear low density polyethylene (LLDPE) or substantially linearethylene polymer, or mixtures thereof). Presently, polyethyleneparticles are preferred. Most preferably, the polyethylene particles arethose sold by Quantum USI Division under the designation “MicrotheneFN500.”

Preferably, the polyolefin particles are present in an amount betweenabout 10 and 75 percent by weight of the dispersion, more preferablybetween about 20 and about 50 percent, and most preferably between about25 and about 33 percent.

The particle size of the polyolefin particles is important both toensure that a good dispersion is achieved and also to ensure that thepolyolefin particles penetrate the yarn and primary backing so as toprovide good abrasion resistance. Preferably, the average particle sizeof the polyolefin particles is between about 1 and about 1000 microns,and more preferably between about 5 and 40 microns. The most preferredpolyethylene particles referred to above have an average particle sizeof about 18 to about 22 microns (e.g., 20 microns).

Preferably, the polyolefin particles have a Vicat softening point (asmeasured in accordance with ASTM D1525) between about 50 and about 100°C., and more preferably between about 75 and 100° C. The most preferredpolyethylene particles referred to above have a softening point of about80° to about 85° C. (e.g., 83° C.).

When polypropylene particles are used, they preferably have a melt flow(ASTM D-1238 Condition 210/2.16) between about 1 to about 80, mostpreferably between about 60 and about 80. When polyethylene particlesare used, they preferably have an I₂ melt index (ASTM D-1238 Condition190/2.16) between about 1 and about 100 g/10 minutes, and morepreferably between about 20 and about 25 g/10 minutes. The mostpreferred polyethylene particles referred to above have an I₂ melt indexof t 22 g/10 minutes.

Ethylene acrylic acid (EAA) may be used for the polyolefin particles,preferably in combination with polyethylene or polypropylene particles.It has been found that EAA can increase the adhesion of the pre-coat tothe yarn and primary backing, as well as to a thermoplastic sheetextruded thereon.

The aqueous dispersion preferably contains other ingredients. Forexample, a surfactant is preferably included to aid in keeping thepolyolefin particles dispersed. Suitable surfactants are nonionic,anionic, cationic and fluorosurfactants. Preferably, the surfactant ispresent in an amount between about 0.01 and about 1 weight percent basedon the total weight of the dispersion. More preferably, the surfactantis anionic. Most preferably, the surfactant is one sold by Ciba Geigyunder the designation “Igepal C0430” and is present at 0.1 weightpercent based on the total weight of the dispersion.

A thickener is also preferably included to provide a suitable viscosityto the dispersion. Preferably, the thickener is one selected from thegroup consisting of sodium and ammonium salts of polyacrylic acids andis present in an amount between about 0.1 and about 2 weight percentbased on the total weight of the dispersion. Most preferably, thethickener is a salt of a polyacrylic acid such as that sold by Sun ChemInternational under the designation “Print Gum 600” and is present atabout 0.8 weight percent based on the total weight of the dispersion.

Preferably, the viscosity of the dispersion measured on a Brookfield RVTviscometer is between about 3000 cP (centipoises) at 20 rpm with a No. 5spindle and about 50,000 cP at 2.5 rpm with a No. 5 spindle measured at23° C. Most preferably, the viscosity of the dispersion is between about10,000 and 20,000 cP at 2.5 rpm with a No. 5 spindle.

In addition, the dispersion preferably includes a defoaming agent.Preferably, the defoaming agent is a non-silicone defoaming agent and ispresent in an amount between about 0.01 and about 1.0 weight percentbased on the total weight of the dispersion. Most preferably, thedefoamer is one such as that sold by LENMAR Chemical Corporation underthe designation “MARFOAM N-24A” and is present at about 0.1 weightpercent based on the total weight of the dispersion.

Preferably, the aqueous dispersion further includes a dispersionenhancer, such as fumed silica which has been found to act as acompatibilizer for the dispersion, thus allowing the use of largerpolyolefin particles. Preferably, the fumed silica is present at betweenabout 0.1 and about 0.2 weight percent based on the total weight of thedispersion. Most preferably, the fumed silica is one such as that soldby DeGussa under the designation “Aerosil 300.”

The aqueous dispersion of polyolefin particles can be made up in variousways. Preferably, the ingredients are added to the water in thefollowing order: surfactant, defoamer, polyolefin, thickener. Themixture is then agitated in a homogenous mixer, preferably with highshear mixing, until all lumps have dispersed, typically for about 8 toabout 12 minutes (e.g., 10 minutes).

The dispersion can be applied to the carpet in various ways. Forexample, the dispersion can be applied directly, such as with a rollover roller applicator, or a doctor blade. Alternatively, the dispersioncan be applied indirectly, such as with a pan applicator. Preferably, aroll over roller applicator is used with the top roller turning at about22 to about 27 percent of line speed (e.g., 25 percent of line speed).

The amount of dispersion applied and the concentration of the particlescan be varied depending on the desired processing and productparameters. Preferably, the amount of dispersion applied and theconcentration of the particles are selected so as to apply between about4 and about 12 ounces per square yard (OSY) (about 141.5 and about 424.4cm³/m²) of carpet. Most preferably, this is achieved by using adispersion containing about 50 weight percent polyolefin particles(based on the total weight of the dispersion) and applying between about8 and about 10 OSY (about 283 and about 353.7 cm³/m²) of the dispersion.

After application of the dispersion, heat is applied to the back side ofthe primary backing so as to dry the dispersion and to at leastpartially melt the particles. As a result, the loops of yarn are fixedto the primary backing. Preferably, the heat is applied by passing theproduct through an oven. Such an oven is preferably set at a temperaturebetween about 100 and about 150° C. and the product spends between about2 and about 5 minutes passing through the oven. Also, since the objectis to at least partially melt the particles, the temperature of the ovenis set at between about 5 and about 75° C. above the Vicat softeningpoint of the polyolefin particles.

After treatment with the dispersion of polyolefin particles, the carpetmay be used as is or, more preferably, may have an additional backingapplied thereto. Additional backings can be applied by various methodswith the preferred method, as described above, involving the use of anextruded sheet of a thermoplastic material, preferably the homogeneouslybranched ethylene polymer described above, onto which a conventionalsecondary backing is laminated. In particular, a molten thermoplasticmaterial is preferably extruded through a die so as to make a sheetwhich is as wide as the carpet. The molten, extruded sheet is applied tothe back side of the primary carpet backing. Since the sheet is molten,the sheet will conform to the shape of the loops of yarn and furtherserve to fix the loops in the primary backing.

Extrusion coating configurations include a monolayer T-type die,singe-lip die coextrusion coating, dual-lip die coextrusion coating, andmultiple stage extrusion coating. Preferably, the extrusion coatingequipment is configured to apply a total coating weight of between about4 and about 30 ounces/yd² (OSY) (about 141.5 and about 1061.1 cm³/m²),with between about 18 OSY (about 636.7 cm³/m²) and about 22 OSY (about778.1 cm³/m²), e.g., 20 OSY, (707.4 cm³/m²) being most preferred.

Measured another way, the thickness of an unexpanded, collapsedextrusion coated adhesive backing material is in the range from about 6to about 80 mils, preferably from about 10 to about 60 mils (about 0.25to about 1.52 mm), more preferably from about 15 to about 50 mils (about0.38 to about 1.27 mm), and most preferably from about 20 to about 40mils (about 0.51 to about 1.02 mm).

The line speed of the extrusion process will depend on factors such asthe particular polymer being extruded, the exact equipment being used,and the weight of polymer being applied. Preferably, the line speed isbetween about 18 and about 250 ft./min. (about 5.5 and about 76.2m/min.), more preferably between about 80 and about 220 ft./min. (about24.4 and about 67.1 m/min.), most preferably between about 100 and about200 ft./min. (about 30.5 and about 61 m/min.).

The extrusion coating melt temperature principally depends on theparticular polymer being extruded. When using the most preferredsubstantially linear polyethylene described above, the extrusion coatingmelt temperature is greater than about 450° F. (232° C.), preferablygreater than or equal to about 500° F. (about 260° C.), or is betweenabout 450° (about 232° C.) and about 650° F. (about 343° C.), morepreferably between about 475° (about 246° C.) and about 600° F. (about316° C.), most preferably between about 500° and about 550° F. (about260° and about 288° C.).

Preferably, two layers of resin, each layer comprising a differentresin, are extruded with the layer applied directly onto the backside ofthe primary backing material (first layer) having a higher melt indexthan the second layer which is applied onto the backside of the firstlayer. Since it is the first layer which is relied on to encapsulate andpenetrate the yarn, this layer should have a melt index high enough(melt viscosity low enough) to promote encapsulation and penetration ofthe yarn. The second layer, which is generally not relied on toencapsulate and penetrate the yarn, may be used either as the bottomsurface of the carpet or to facilitate the application of an optionalsecondary backing material. For both of these uses, it is preferred tohave a lower melt index to provide higher strength after cooling. Inaddition, because it is not relied on for encapsulating or penetratingthe fiber bundles, a resin of lower quality and/or less tightlycontrolled properties may be used in the second layer. In a preferredembodiment, the second layer is a recycled feedstock.

Also, the first and second layers may consist of different polymerchemistries or compositions. For example, the first layer can becomprised of an adhesive polymer (as an additive or as the compositionof the entire layer) such as, but not limited to, an ethylene vinylacetate copolymer, an ethylene acrylic acid copolymer or a maleicanhydride/ethylene polymer graft (preferably, a substantially linearethylene polymer/maleic anhydride extrusion graft or a high densitypolyethylene/maleic anhydride extrusion graft) and the second layer canbe comprised of a non-polar polymer such as a homogeneously branchedethylene polymer, a low density polyethylene or ultra low densitypolyethylene. Alternately, the first layer can be comprised of anon-polar polymer and the second layer can be comprised of an adhesivepolymer.

Preferably, the first layer has an 12 melt index between about 30 andabout 175 g/10 min. and the second layer has an 12 melt index betweenabout 1 and about 70 g/10 min. Most preferably, the first layer has an12 melt index between about 30 and about 70 g/10 min and the secondlayer has an 12 melt index between about 10 and about 30 g/10 min.

It is also preferred to extrude two layers of a single polymercomposition so as to have greater control over the thickness or weightof the resin applied to the carpet. In alternative embodiments, three ormore layers of the resin can be extruded on the back surface of theprimary backing material to achieve even higher coat weights and/or toobtain a more gradual transition between the first and last layerapplied. Preferably, a dual lip die is used to apply two layers.Alternatively, two or more extrusion stations or a single lipcoextrusion die can be used to apply these two or more layers.

Another aspect of the present invention is the use of modifiedhomogeneously branched ethylene polymers. In particular, in certainaspects of the invention the at least one homogeneously branchedethylene polymer that is employed as the adhesive backing material,primary backing material or yarn, preferably as the adhesive backingmaterial, is modified by the addition of at least one adhesive polymericadditive. Suitable adhesive polymeric additives include polymer productscomprised of (1) one or more ethylenically unsaturated carboxylic acids,anhydrides, alkyl esters and half esters, e.g., acrylic acid,methacrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaricacid, crotonic acid and citraconic acid, citraconic anhydride, succinnicacid, succinnic anhydride, methyl hydrogen maleate, and ethyl hydrogenmaleate; esters of ethylenically unsaturated carboxylic acids, e.g.,ethyl acrylate, methyl methacrylate, ethyl methacrylate, methylacrylate, isobutyl acrylate, and methyl fumarate; unsaturated esters ofcarboxylic acids, e.g., vinyl acetate, vinyl propionate, and vinylbenzoate; and ethylenically unsaturated amides and nitriles e.g.,acrylamide, acrylonitrile, methacrylonitrile and fumaronitrile; and (2)one or more ethylenically unsaturated hydrocarbon monomers such asaliphatic α-olefin monomers, e.g., ethylene, propylene, butene-1 andisobutene; conjugated dienes, e.g., butadiene and isoprene; andmonovinylidene aromatic carbocyclic monomers, e.g., styrene,α-methylstyrene, toluene, and t-butylstyrene. Suitable adhesivepolymeric additives can be conveniently prepared by known techniquessuch as, for example, by interpolymerization or by a polymerizationprocedure followed by a chemical or extrusion grafting procedure.Suitable grafting techniques are described in U.S. Pat. Nos. 4,762,890;4,927,888; 4,230,830; 3,873,643; and 3,882,194, the disclosures of allof which are incorporated herein by reference.

Preferred adhesive polymeric additives for use in the present inventionare maleic anhydride grafts wherein maleic anhydride is grafted onto anethylene polymer at a concentration of about 0.1 to about 5.0 weightpercent, preferably about 0.5 to about 1.5 weight percent. The use ofethylene polymer/maleic anhydride grafts as adhesive polymeric additivesin the present invention significantly improves the performance andoperating window of extrusion coated homogeneously branched ethylenepolymers as the adhesive backing material, especially for polar polymersuch as for example, but not limited to, nylon and polyester facedcarpets. The improvement pertained to substantially higher comparativeabrasion resistance and tuft bind strength. The improvement wassurprising in that graft adhesives are generally known to requireextended molten or semi-molten contact times for improved performanceand function as interlayer adhesives for films and coatings where thereis a continuous substrate as opposed to the discontinuous interfaceexistent in carpet construction.

Preferred ethylene polymers for use as the grafted host polymer includelow density polyethylene (LDPE), high density polyethylene (HDPE),heterogeneously branched linear low density polyethylene (LLDPE),homogeneously branched linear ethylene polymers and substantially linearethylene polymers. Preferred host ethylene polymers have a polymerdensity greater than or equal to 0.915 g/cc and most preferably greaterthan or equal to 0.92 g/cc. Substantially linear ethylene polymers andhigh density polyethylene are the preferred host ethylene polymers.

In this aspect of the present invention, the adhesive polymeric additiveis added to the homogeneously branched ethylene polymer at a level inthe range of from about 0.5 to about 30 weight percent, preferably fromabout 1 to about 20 weight percent, more preferably from about 5 toabout 15 weight percent based on the total weight of the polymer. Forthe preferred ethylene polymer maleic anhydride grafts, additions shouldprovide a final maleic anhydride concentration in the range of fromabout 0.01 to about 0.5 weight percent, preferably from about 0.05 toabout 0.2 weight percent based on the total weight of the polymer.

Auxiliary equipment such as a pre-heater can be used. In particular, aheater, such as a convection oven or infrared panels can be used to heatthe back of the greige good before the adhesive backing material isextruded thereon. In doing so, it has been found that the encapsulationand penetration of the yarn bundles can be enhanced. Preferably, thepre-heater is an infrared unit set at between about 200 and about 1500°C. and the greige good is exposed to this heating for between about 3and about 30 seconds. Most preferably, the heater is set at about 1000°C. and the greige good is exposed to this heating for about 5 to about 7seconds (e.g., 6 seconds).

In addition to or as an alternative to pre-heating, the process of theinvention may also employ a post-heat soaking process step to lengthenthe molten time for the adhesive backing material to thereby improve theencapsulation and penetration of the yarn or fiber bundles by theadhesive backing material. Preferably, after the adhesive backingmaterial is applied to the greige good, it is heated by a convectionoven or infrared radiation at a temperature between about 200 and about1500° C. for between about 3 and 30 seconds, most preferably at 1000° C.for about 5 to about 7 seconds (e.g., 6 seconds).

As another piece of auxiliary or optional equipment, a vacuum nip rollcan be used to draw the adhesive backing material extrudate (i.e.,semi-molten or molten polymer web) onto the greige good. In a properlyconfigured extrusion coating operation, the pile face of the greige goodis positioned towards the vacuum nip roll and the polymer web is drawdown onto the back surface of the primary backing material of the greigegood. Vacuum nip roll 24 (which is illustrated in FIG. 2 and isavailable from Black Clawson Corporation) is suitable for vacuum drawingthe adhesive backing material web. Vacuum nip roll 24 can be adaptedfrom a conventional nip roll wherein a portion of the hollow internal ofthe roll is partitioned, dedicated and coupled to a external vacuum pump27 to provide a vacuum surface. The surface of the vacuum portion isperforated but machined flush and continuously with the remainingsurface of the roll. Suitable vacuum nip rolls can have a complete 360degree vacuum surface; however, a vacuum surface of from about 10 toabout 180 degrees is preferred, most preferably about 60 degrees. Toeffectively draw the adhesive backing material web onto the greige goodand maximize to the penetration of the yarn or fiber bundles, the vacuumis set to greater than 15 inches of H₂O (3.7 Pa), preferably greaterthan or equal to 25 inches of H₂O (6.1 Pa) and more preferably greaterthan or equal to 40 inches of H₂O (9.8 Pa), or from between about 15 andabout 50 inches of H₂O (about 3.7 and about 12.3 Pa), preferably frombetween about 20 and about 45 (about 4.9 and about 11.1 Pa).

The length of time the greige good is actually subjected to the vacuumwill primarily depend on the extrusion coating line speed and the extentof draw on the adhesive backing material web will largely depend on thelevel of vacuum and the porosity of the greige good. As such, highervacuum levels will be required for higher extrusion coating line speedsand/or denser greige good to effectively the draw the adhesive backingmaterial.

In addition to or as an alternative to a vacuum nip roll, a highpressure positive air device such as an air blade or knife can also beused to force the adhesive backing material web onto the back surface ofthe primary backing material. Preferably, the positive air pressuredevice is set to provide an air pressure greater than 20 psi (0.14 MPa),preferably greater than or equal to 40 psi (0.27 MPa), more preferablygreater than or equal to 60 psi (0.41 MPa), or between about 20 andabout 120 psi (about 0.14 and about 0.82 MPa), most preferably betweenabout 30 and about 80 psi (about 0.20 and about 0.54 MPa) Preferably,the positive air pressure device is positioned at the extrusion coatingnip, extends across the entire width of the polymer web and ispositioned behind the polymer web towards the chill roll so to force thepolymer web onto the greige good and press the polymer web into the yarnor fiber bundles.

The extruded polymer(s) can either be used neat, or can have one or moreadditive included. A preferred additive is an inorganic filler, morepreferably, an inorganic filler with a high heat content. Examples ofsuch fillers include, but are not limited to, calcium carbonate,aluminum trihydrate, talc, barite. High heat content fillers arebelieved to be advantageous in the invention because such fillers allowthe extrudate to remain at elevated temperatures longer with thebeneficial result of providing enhanced encapsulation and penetration.That is, normally fillers are added to carpet backing materials tomerely add bulk (i.e. as extenders) or to impart insulating and sounddampening characteristics. However, we have found that inorganic mineralfillers that have high heat contents surprisingly improve yarnencapsulation and penetration which in turn improves the performance ofthe abrasion resistance and tuft bind strength of extrusion coatedcarpet samples.

Preferably, a high heat content filler is added at a level of betweenabout 1 and about 75 weight percent of the total extrudate, morepreferably between about 15 and about 60 weight percent and mostpreferably between about 20 weight percent and 50 weight percent. Suchfillers will have a specific heat content of greater than or equal to0.4 cal-cc/° C. (1.8 Joules-cc/° C.), preferably greater than or equalto 0.5 cal-cc/° C. (2 Joules-cm³/° C.), more preferably greater than orequal to 0.6 cal-cc/° C. (2.5 Joules-cm³/° C.), and most preferablygreater than or equal to about 0.7 cal-cc/° C. (2.9 Joules-cm³/° C.).Representative examples of high heat content fillers for use in thepresent invention include, but are not limited to, limestone (primarilyCaCO₃), marble, quartz, silica, and barite (primarily BaSO₄). The highheat content fillers should be ground or precipitated to a size that canbe conveniently incorporated in an extrusion coating melt stream.Suitable particle sizes range from about 1 to about 50 microns.

If a foamed backing is desired on the carpet, a blowing agent can beadded to the adhesive backing material and/or the optional secondarybacking material. If used, the blowing agents are preferablyconventional, heat activated blowing agents such as azodicarbonamide,toluene sulfonyl semicarbazide, and oxy bis(benzene sulfonyl) hydrazide.The amount of blowing agent added depends on the degree of foamingsought. A typical level of blowing agent is between about 0.1 and about1.0 weight percent.

Implosion in the present invention is accomplished by restrictingexpansion of the adhesive backing material in the direction opposite theprimary backing material during activation of the implosion agent suchthat the molten polymer is forced into the interior and free space ofthe yarn or fiber bundles. An imploded adhesive backing material willhave a collapsed, non-expanded matrix (relative to a foamed backing) andbe of essentially the same thickness (measured from the plane of theback surface of the primary backing material) as would be the casewithout the use of the implosion agent. That is, the adhesive backingmaterial layer would be characterized as not being expanded by theimplosion agent.

The implosion agent is selected and formulated into the adhesive backingmaterial and extrusion conditions are set such that the activation ofthe implosion agent occurs at the instant of nip while the adhesivebacking material is still semi-molten or molten. With improved yarnpenetration accomplished with the use of an implosion agent, the carpetwill exhibit comparatively improved abrasion resistance. Thus, the useof an implosion agent can allow the use of polymer compositions havinglower molecular weights to provide improved extrusion coatability yetmaintain higher abrasion resistance (i.e., comparable to adhesivebacking materials based on higher molecular weight polymercompositions). An effective amount of implosion agent would be betweenabout 0.1 and about 1.0 weight percent based on the weight of theadhesive backing material.

Conventional blowing agents or any material that ordinarily functions asa blowing agent can be used as an implosion agent in the presentinvention providing expansion of the adhesive backing material matrix issuitably restricted or confined when the material is activated such thatmolten polymer is forced into the interior and free space of the yarn orfiber bundles and there is no substantial expansion of the adhesivebacking material as a result of having used the implosion agent.However, preferably, an imploded adhesive backing material will becharacterized as having a closed cell structure that can be convenientlyidentified by photomicrographs at 50× magnification.

Other additives can also be included in the adhesive backing material,to the extent that they do not interfere with the enhanced propertiesdiscovered by Applicants. For example, antioxidants such as stericallyhindered phenols, sterically hindered amines and phospites may be used.Suitable antioxidants include Irganox® 1010 from Ciba-Geigy which is ahindered phenol and Irgafos® 168 from Ciba-Geigy which is a phosphite.Other possible additives include antiblock additives, pigments andcolorants, anti-static agents, antimicrobial agents (such as quaternaryammonium salts) and chill roll release additives (such as fatty acidamides).

As noted above, and shown in FIG. 2, the carpet of the inventionpreferably also includes a secondary backing material. Preferably, thesecondary backing material is laminated directly to the extrudedlayer(s) while the extrudate is still molten after extrusion coating. Ithas been found that this technique can improve the penetration of theextrusion coating into the primary backing.

Alternatively, the secondary backing material can be laminated in alater step by reheating and/or remelting at least the outermost portionof the extruded layer or by a coextrusion coating technique using atleast two dedicated extruders. Also, the secondary backing material canbe laminated through some other means, such as by interposing a layer ofa polymeric adhesive material between the adhesive backing material andthe secondary backing material. Suitable polymeric adhesive materialsinclude, but are not limited to, ethylene acrylic acid (EAA) copolymers,ionomers and maleic anhydride grafted polyethylene compositions.

The material for the secondary backing material can be a conventionalmaterial such as the woven polypropylene fabric sold by AMOCO under thedesignation Action Bac®. This material is a leno weave withpolypropylene monofilaments running in one direction and polypropyleneyarn running in the other. More preferably, the secondary backingmaterial used with the present invention is a woven polypropylene fabricwith monofilaments running in both directions. A suitable example ofsuch a material is sold by Amoco under the designation Style 3878. Thismaterial has a basis weight of 2 OSY (70.7 cm³/m²). This material withmonofilaments running in both directions has been found beneficial inproviding enhanced dimensional stability to the carpet.

In an alternatively preferred embodiment, the secondary backing materialis a material known as fiber lock weave or “FLW.” FLW is a fabric whichincludes fibers needle punched into it. Sometimes FLW is used as aprimary backing material on a carpet with a low pile weight. In suchcarpet, the fibers protrude on the pile side so as to help keep theprimary backing material from showing through the pile. However, in thisalternatively preferred embodiment, FLW is used as the secondary backingmaterial with the needle punched fibers protruding away from the carpet.Doing so has been found to enhance the adhesion of the carpet wheninstalled with a glue-down adhesive. In particular, the surface area forcontacting the glue-down adhesive is increased and the protruding fibershelp to anchor the carpet backing to the glue-down adhesive.

Alternatively, the secondary backing material can be a non-woven fabric.Several types are available, including, but not limited to, spun-bond,wet-laid, melt-blown, and air entangled. As noted above, it is preferredthat the secondary backing is made from a polyolefin to facilitaterecycling.

In an alternatively preferred embodiment, the non-woven fabric isspun-bond polypropylene fabric, such as that available from Don & LowNon-wovens under the name “Daltex.” Typically, spun-bond fabric is madefrom extruded and air-drawn polymer filaments which are laid downtogether and then point bonded, for example by a heated calendar roll.The basis weight of such a spun-bond secondary backing can be varied,preferably between 35 and 80 grams/m² (gsm) more preferably between 60and 80 gsm. Most preferably, the basis weight is 77-83 gsms (e.g., 80gsm). One factor favoring a higher basis weight for the spun-bond fabricis that the higher basis weight fabric is less likely to be melted whenbrought into contact with the molten extruded backing.

It has been found that a spun-bond non-woven fabric is advantageous touse as a secondary backing in the present invention because the porousnature of the fabric increases the surface area of the carpet for gluingthe carpet to the floor.

In still another alternatively preferred embodiment, the secondarybacking is a woven polypropylene fabric such as Action Bac® from Amocowhich has been enhanced by having 2 OSY (70.7 cm³/m²) of polypropylenefibers needle punched onto one side of it. This needle punched fabric islaminated so as to have the polypropylene fibers embedded within theadhesive backing layer. As a result, the strands of the wovenpolypropylene fabric exposed. This embodiment has been shown to haveimproved glue down properties as compared to an embodiment without theneedle punched fibers because, without the needle punched fibers, thestrands of the woven polypropylene fabric are at least partiallyembedded in the adhesive backing layer. As such, the surface area forgluing is reduced. It was also noted that the back of the carpet made inthis embodiment was much less abrasive than that found with traditionallatex backed carpet. The carpet is also more flexible than traditionallatex backed carpet. Consequently, this embodiment is preferred formaking areas rugs and the like.

Still other materials can be used for the secondary backing. Forexample, if an integral pad is desired, a polyurethane foam or othercushion material can be laminated to the back side of the carpet. Suchbackings can be used for broadloom carpet as well as for carpet tile.

The extrusion backed carpet construction and the methods describedherein are particularly suited for making carpet tile. FIG. 6 shows across-section of a carpet tile 100 made according to the presentinvention. A yarn 103, preferably made of polypropylene, is tufted intoa primary backing 101, which is also preferably made of polypropylene,so as to leave a carpet pile face 104 on top of the primary backing 101and back stitches 105 below the primary backing. Applied to the back ofthe primary backing 101 and the back stitches 105 is an adhesive layer107. Preferably, this adhesive layer is made from a polyolefin. Morepreferably, the adhesive layer is made from the ethylene polymersdescribed in detail above. Most preferably, this adhesive layer 107 ismade from a substantially linear ethylene polymer with the additivesdescribed in Example 194 below.

In a preferred embodiment of carpet tile, the carpet included from about5 to about 200 OSY (about 176.8 to about 7,074 cm³/m²) of extrudedadhesive backing. More preferably, the carpet for tile includes fromabout 30 to about 80 OSY (about 1061 to about 2,830 cm³/m²) of extrudedbacking, most preferably, 50 OSY (1,768 cm³/m²).

Preferably, the carpet for carpet tile receives its extruded backing intwo passes, i.e., to apply two layers of the extruded backing. The firstpass applies the layer 107 in FIG. 6. Preferably this layer 107 isbetween about 2.5 and about 100 OSY (about 88.4 to about 3,537 cm³/m²)of the extruded polymer, more preferably between about 15 and about 40OSY (about 530.5 to about 1,415 cm³/m²), and most preferably 25 OSY (884cm³/m²). The second pass adds the layer 111. Preferably the second layer111 is about 2.5 and about 100 OSY (about 88.4 to about 3,537 cm³/m²),more preferably between about 15 and 40 OSY (about 530.5 to about 1,415cm³/m²), and most preferably 25 OSY (884 cm³/m²).

Applying the extruded backing in two passes allows the opportunity toapply a first and second layer which have different physical and/orchemical properties. As noted above, it is sometimes preferable to applya polymer with a higher melt index adjacent the primary backing, and apolymer with a lower melt index below that. In addition, it can also bepreferably to use an extrudate with a lower filler content in the layernext to the primary backing and an extrudate with a higher fillercontent in the layer below that. In one preferred embodiment, the layernext to the primary backing includes a filler loading of 30 percent byweight and the layer below that includes a filler loading of 60 percentby weight. The lower filler content is believed to provide betterpenetration of the primary backing and back stitches in the carpet bythe extrudate.

When making carpet tile, it is preferable to embed a layer ofreinforcing material 109 between the first and second layers ofextruding backing. An important property of carpet tile is dimensionalstability, i.e., the ability of the tile to maintain its size andflatness over time. The inclusion of this layer of reinforcing materialhas been found to enhance the dimensional stability of carpet tile madeaccording to this preferred embodiment. Suitable reinforcing materialsinclude dimensionally and thermally stable fabrics such as non-woven orwet-laid fiberglass scrims, as well as woven and non-woven thermoplasticfabrics (e.g. polypropylene, nylon and polyester). Most preferably, thereinforcement layer is a polypropylene non-woven fabric sold by Reemayas “Typar” with a basis weight of 3.5 OSY (124 cm³/m²). Alternatively, apreferred reinforcement layer is a fiberglass scrim sold by ELK Corp. as“Ultra-Mat:” with a basis weight of 1.4 OSY (49.5 cm³/m²).

The carpet tile may include a secondary backing fabric 113 below thesecond layer of extruded backing 111. Suitable materials for thesecondary backing fabric include those described above. However, it ispresently not preferred to include a secondary backing fabric on carpettile.

FIG. 7 schematically shows a preferred line 120 for making carpet tileaccording to the present invention. A length of greige good 121, i.e.yarn tufted into a primary backing, is unrolled from the roll 123. Thegreige good 121 passes over the rollers 125 and 127 with the primarybacking toward the roller 123. Between rollers 125 and 127 is apre-heater 129 as described above.

An extruder 131 is mounted so as to extrude a sheet 135 of the polymericbacking through the die 133 onto the back of the greige good at a pointbetween the roller 127 and the nip roll 141. The exact location at whichthe sheet 135 contacts the greige good can be varied depending on theline speed and the time desired for the molten polymer to rest on thegreige good before passing between the nip roll 141 and the chill roll143. At present it is preferred that the sheet 135 contact the greigegood so as to lie on the greige good for between about 0.5 and about 2seconds, most preferably about 1 second, before passing between the niproll 141 and the chill roll 143.

In this preferred depicted embodiment, a scrim of non-wovenpolypropylene 139 is fed from roll 137 so as to contact the chill roll143 at a point just prior to the nip roll 141. As a result, the scrim139 which will act as a reinforcing fabric in the finished carpet tileis laminated to the greige good through the polymer.

The pressure between the nip roll 141 and the chill roll 143 can bevaried depending on the force desired to push the extruded sheet. Mostpreferably, there is 60 psi (0.41 MPa) of air pressure pushing the rollstogether. Also, as described in connection with FIG. 2, it may bedesirable to include a vacuum slot in the nip roll. In addition, a jetof pressurized air may also be used to push the extruded sheet into thecarpet backing.

The size of the chill roll 143 and the length of time the carpet rollsagainst it can be varied depending on the level of cooling desired inthe process. Preferably the chill roll 143 is cooled by simply passingambient water through it.

After passing over the chill roll 143, the carpet is brought overrollers 145 and 147 with the carpet pile toward the rollers. A secondextruder 149 extrudes a sheet of polymer 153 through its die 151 on tothe back of the scrim 139. Again the point at which the extruded sheet153 contacts the scrim 139 can be varied as described above.

At this point, if a secondary backing fabric is desired for the carpettile, that fabric can be introduced from a roll similar to that shown at137 so as to contact the be laminated to the carpet through the extrudedsheet 153 as it passes between the nip roll 155 and the chill roll 153.Such a secondary backing fabric is not currently preferred for carpettile construction.

The carpet passes between the nip roll 155 and the chill roll 157.Again, the pressure applied between the two rolls 155 and 157 can bevaried. At present, 60 psi (0.41 MPa). of air pressure is preferablyapplied against the nip roll 155.

After passing around the chill roll 157, the carpet passes around roll159 and is preferably passed over an embossing roll (not shown) to printa desired pattern on the back of the carpet.

While the apparatus shown in FIG. 7 is preferred for making a carpettile with two layers of extruded backing and a reinforcing fabric inbetween, the same construction can be made with a single extrusion die,nip roll and chill roll. In particular, the first layer of extrudedbacking and the reinforcing fabric can be applied in a first passthrough the line after which the carpet is rolled up. The second layerof extruded backing can be applied on top of the reinforcing fabric in asecond pass through the same line after which the carpet is ready to becut into carpet tiles.

Carpet tile is typically made by producing a length of backed carpet andthen cutting the carpet into the appropriate sized squares. In theUnited States, the most common size is 18 inches (45.7 cm) square. Inthe rest of the world, the most common size is 50 cm square.

In still another alternative embodiment, a pressure sensitive adhesiveis applied to the bottom surface of the backed carpet and a releasesheet is included. In this way, a “peel and stick” carpet is produced.This is particularly beneficial when the carpet is to be cut into tiles.Examples of suitable pressure sensitive adhesives include ethylene vinylacetate copolymers and substantially linear ethylene polymers formulatedwith tackifiers and polymeric waxes. The release sheet can be made fromconventional polymers and/or paper products. Preferably, the releasesheet is made of polyester/wax formulation.

It has been determined that the pressure sensitive adhesive is bestapplied directly to the adhesive backing material while the adhesivebacking material is still at an elevated temperature from the extrusioncoating process. A preferred technique is to extrusion laminate thepressure sensitive adhesive with the adhesive backing material; that is,to apply the pressure sensitive adhesive at nip. Alternately, theadhesive backing material can be reheated before the pressure sensitiveadhesive is applied.

Another preferred embodiment of the present invention, exclusive of anoptional secondary backing material, involves the combination of thevarious process steps described herein together with the use of at leastone substantially linear ethylene polymer with an effective amount of animplosion agent formulated therein in the first layer of a two layeradhesive backing material. The a preferred combination of process stepsat least includes pre-coating with an aqueous polyolefin system; removalof processing materials by washing or scouring the greige good with anaqueous detergent solution heated to at least 67° C.; drying andpre-heating the greige good by subjecting it to infra-red radiation setat about 1000° C. for about 1 to about 6 seconds; extrusion coating theadhesive backing material onto the back surface of the pre-heated,washed primary backing material by utilizing extrusion melt temperaturesof greater than or equal to 615° F. (324° C.); subjecting thesemi-molten or molten adhesive backing material web to a vacuum ofgreater than 40 inches H₂O (9.8 Pa) while at the extrusion coating nip;subjecting the semi-molten or molten adhesive backing material to apositive air pressure device set at greater than about 60 psi (0.41 MPa)at the extrusion coating nip; activating an implosion agent while at theextrusion coating nip; and heat soaking of the carpet by subjecting itto infra-red radiation set at about 1000° C. for about 1 to about 6seconds.

Various embodiments of the present invention were evaluated and, inspecific instances, compared to prior art embodiments. However, theExamples shown should in no way limit the scope of the present inventionto such Examples.

EXAMPLES Test Methods

The primary performance criteria determined for the various Examplesincluded: tuft bind, abrasion resistance, Velcro rating, flexibility andlamination strength. Tuft bind testing was conducted in accordance withASTM D-1335-67.

Moduli for the ethylene polymers used in the present invention weremeasured in accordance with ASTM-790.

Abrasion resistance was based on a qualitative Velcro fuzzing test. Inthis test, a 2 inch (5.1 cm) diameter, 2 pound (0.91 kg) roller coatedwith the loop side of standard Velcro was passed 10 times over the faceside of coated carpet samples. The fuzz on the abraded carpet was thencompared to a set of carpet standards and rated on a 1-10 scale whereina rating of 10 denoted zero fuzzing.

Flexibility rating was also based on a qualitative assessment.Lamination strength was based on manual qualitative assessment in whicha good delamination rating was given if the various layers of a carpetsample could not be manually pulled apart (i.e., separation of theadhesive backing material from the primary backing material), while apoor rating was given if layers delaminated.

The Aachen test is used to determine the dimensional stability of carpettile. The Aachen test used herein is ISO Test Method 2551. Brieflydescribed, carpet tiles are first measured in the machine andcross-machine dimensions and then exposed to heat (140° F. (60° C.) for2 hours) and moisture (submerged in water for 2 hours). The carpet tilesare dried for 16 hours in a drying oven. The tiles are then put into aconditioning room for 48 hours, after which each tile is measured in themachine and cross-machine directions. The results are given in terms ofa percent change from the original dimensions.

Resins

Table 1 lists the various ethylene polymers used to prepare the variousExamples.

TABLE 1 Melt Index Density Modulus Resin Type (gm/10 min) (gm/cc) psi(MPa) A SLEP 30 0.871   2,560 (17.4) B SLEP 30 0.885   5,400 (36.7) CSLEP 30 0.900  13,700 (93.2) D SLEP 10 0.900 ND E SLEP 13 0.871 ND FSLEP 75 0.871 ND G SLEP 75 0.900 ND H SLEP 175 0.900 ND I HBLEP 35 0.882ND J* LLDPE 5.4 0.921 ND K* LDPE 12 0.916 23,500 (160) L* LDPE 120 0.92243,000 (293) M* LDPE 150 0.913 ND N* ULDPE 6 0.911 ND O* ULDPE 1 0.91226,700 (182) P* LLDPE 1 0.920 38,000 (259) Q* HDPE 10 0.960 182,000(1238) R* ULDPE 30 0.913 28,400 (193) S* LDPE 55 0.922 41,000 (279) SLEPdenotes a substantially linear ethylene/1-octene copolymer availablefrom The Dow Chemical Company. HBLEP denotes a homogeneously branchedlinear ethylene polymer such as Exact ™ resin available from the ExxonCorporation. LLDPE denotes a linear low density ethylene/1-octenecopolymer such as a Dowlex ™ resin available from The Dow ChemicalCompany. ULDPE denotes an ultra low density linear ethylene/1-octenecopolymer such as an ATTANE ™ resin available from The Dow ChemicalCompany. LDPE denotes a high pressure ethylene homopolymer such asavailable from various polymer manufacturers. HDPE denotes a highdensity polyethylene resin such as available from various polymermanufacturers. *Denotes that the listed polymer is not suitable for usein certain aspects of the present invention. ND denotes the value wasnot determined.

Examples 1-12

Table 2 summarizes the polymers, extrusion conditions and carpet sampleperformance results for Inventive Examples 1-8 and Comparative Runs9-12. The extrusion coating equipment consisted of a two-extruder BlackClawson coextrusion line equipped with a 3½ inch (8.9 cm) diameterprimary extruder having a 30:1 L/D and a 2½ inch (6.4 cm) diametersecondary extruder with a 24:1 L/D. For these examples, only the largeextruder was operated at 90 rpms (250 lbs./hr). A 76 cm slot die wasattached to the extruder and was deckled to 69 cm with a 20-mil (0.51mm) die gap and a 6-inch (15.2 cm) air/draw gap. The nip roll pressurewas set at 85 psi (0.58 MPa) and the chill roll was controlled at 60° F.(15.6° C.). The targeted extrusion temperatures, line speed and coatingthicknesses are listed in Table 2.

Greige good swatches of polypropylene (26 OSY (919.6 cm³/m²), tufted,loop pile, straight stitch greige goods available from Shaw Industriesunder the designation of Volunteer) were cut and slip sheeted onto Kraftpaper for each Example and candidate resins were extrusion coated ontothe backside of the greige goods. Secondary backing material (2.8 OSY(99 cm³/m²) woven polypropylene scrim known as Action Bac® availablefrom Amoco Chemical Company, Fabrics and Fibers Division) was added tothe backside of greige goods after the disposition of the extrudate atthe die and before the nip pressure rollers to form a laminatestructure. FIG. 2 shows the extrusion coating method and the sequence ofapplication of an extrusion coated adhesive backing material followed bythe application of an optional secondary backing material. In someinstances, greige good swatches were first preheated in a convectionoven at 200° F. (93° C.) for 30 min. After coated samples were aged for24 hours at ambient room temperature and 70% relative humidity, tuftbind, abrasion resistance and delamination were determined.

TABLE 2 Pre- Melt Line Tuft Temp Thick Coat Wt Temp Speed Bind ° F. milOSY ° F. ft/min Lamination lbs. Ex. Resin (° C.) (mm) (cm³/m²) (° C.)(m/min) Flex Strength (kg) 1 C Ambient 21 14.5 500 22 Good Good 8.0(0.53) (513) (260) (6.7) (3.6) 2 D Ambient 20 ND 500 22 Good Good 7.6(0.51) (260) (6.7) (3.4) 3 D Ambient  7 ND 500 65 Good Good 5.0 (0.18)(260) (19.8)  (2.3) 4 A 140 ND 15.5 500 22 Good Good 4.6 (60) (548)(260) (6.7) (2.1) 5 G 140 ND 13.1 500 22 Good Good 7.0 (60) (463) (260)(6.7) (3.2) 6 F 150 ND 11.9 500 30 Good Good 7.0 (66) (421) (260) (9.1)(3.2) 7 E 160 ND 18.9 500 22 Good Good 10.4  (71)  669) (260) (6.7)(4.7) 8 A 160 ND 11.8 550 30 Good Good 7.6 (71) (417) (288) (9.1) (3.4) 9* R 140 ND 17.6 500 22 Stiff Poor 7.1 (60) (623) (260) (6.7) (3.2) 10*J Ambient 20 ND 500 22 Stiff Poor ND (0.51) (260) (6.7) 11* L Ambient 20ND 500 22 Stiff Poor ND (0.51) (260) (6.7) 12* S Ambient 20 ND 500 22Stiff Poor ND (0.51) (260) (6.7) *Denotes Comparative Run Example; theexample is not an example of the present invention. ND denotes the valuewas not determined.

Inventive Examples 1-8 show that homogeneously branched ethylenepolymers result in carpet samples with good flexibility and goodcohesion of the carpet components and that tuft bind and abrasionresistance are dependent on processing conditions. Two high pressureLDPE, a heterogeneously branched LLDPE, and a heterogeneously branchedULDPE extrusion coating (Comparative Runs 9-12) resulted in relativelystiff carpet samples and relatively poor carpet component cohesiveness.

One indication of poor component cohesiveness was relatively lowadhesiveness of the backing material to the primary backing material.Another indication was relatively low penetration of the yarn or fiberbundles with the LDPE, LLDPE and ULDPE extrusion coating resins.

Examples 13-22

Table 3 summarizes the polymers, extrusion conditions, and carpetperformance results for Inventive Examples 13-22. These examples usedthe same extrusion equipment, extrusion conditions and greige goodslisted for Examples 1-12.

TABLE 3 Pre- Melt Line Tuft Temp Thick Temp Speed Bind ° F. mil ° F.ft/min Lamination lbs. Ex. Resin (° C.) (mm) (° C.) (m/min) FlexStrength (kg) 13 C 175  7 425 65 Good Good 3.6 (79) (0.18) (218) (19.8)(1.6) 14 C 175  7 500 65 Good Good 5.4 (79) (0.18) (260) (19.8) (2.4) 15C 175  7 550 65 Good Good 6.3 (79) (0.18) (288) (19.8) (2.9) 16 C 175  7575 65 Good Good 6.6 (79) (0.18) (302) (19.8) (3.0) 17 C 175  7 600 65Good Good 5.3 (79) (0.18) (316) (19.8) (2.4) 18 C 175 15 425 30 GoodGood 6.9 (79) (0.38) (218)  (9.1) (3.1) 19 C 175 15 500 30 Good Good 6.8(79) (0.38) (260)  (9.1) (3.1) 20 C 175 15 550 30 Good Good 8.3 (79)(0.38) (288)  (9.1) (3.8) 21 C 175 15 575 30 Good Good 6.2 (79) (0.38)(302)  (9.1) (2.8) 22 C 175 15 600 30 Good Good 6.2 (79) (0.38) (316) (9.1) (2.8)

Inventive Examples 13-22 show the effect of coating thickness andextrusion temperature on carpet backing performance. In certain aspectsof the present invention, coating thicknesses greater than 7 mils (0.18mm), preferably greater than or equal to 11 mils (0.38 mm), morepreferably greater than or equal to about 15, and most preferablygreater than or equal to 22 mils (0.56 mm) are preferred for extrusionmelt temperatures greater than 550° F. (288° C.), preferably greaterthan or equal to 575° F. (302° C.), more preferably greater than orequal to 600° F. (316° C.) and most preferably greater than or equal to615° F. (324° C.). Practitioners will appreciate that extrusion melttemperature and extrusion line speed are inversely related. That is,lower extrusion temperatures will generally require slower extrusionline speeds to achieve good penetration of the yarn. Practitioners willalso appreciate that at elevated temperatures, thermal stabilizationadditives such as Irganox® 1010 and Irgafos® 168 (both supplied byCiba-Geigy) may be required to achieve the full benefit of the presentinvention such as, for example, adhesive backing material penetration ofthe yarn or fiber bundles greater than 40 percent. Practitioners willalso appreciate that excessive chemical stabilization may adverselyeffect draw down performance, thus additive selection and concentrationmust be balanced against draw down requirements and penetrationrequirements. However, in general, higher additive concentrations willbe required at higher extrusion melt temperatures.

Examples 23-54

Table 4 summarizes the polymers, extrusion conditions and carpetperformance results for Examples 23-54. In this evaluation, theextrusion coating equipment consisted of a 3½ inch (8.9 cm) diameterBlack Clawson Model 435 extruder equipped with a 30:1 L/D screw, a 150hp (311 Joules/hr) Electro Flight drive system, a Cloreren 3-layerfeedblock, and a Black Clawson Model 300 XLHL 30″ coat hanger dieexternally deckled to 24 inches (61 cm) using a 20 mil (0.51 mm) die gapand a 6 inch (15.2 cm) air/draw gap. The targeted extrusiontemperatures, screw speed, line speed and coating thicknesses are listedin Table 4.

Samples of polypropylene greige goods (26 OSY (920 cm³/m²), tufted, looppile, straight stitch greige goods supplied by Shaw Industries under thedesignation of Volunteer) were used. Candidate ethylene polymers wereextrusion coated onto the backside of greige goods that were runcontinuously through the extrusion coater rather than slip sheeted asindividual greige good swatches. Electric and gas-fired infrared heaterswere installed prior to the coating station to preheat the greige goods.A partitioned vacuum pressure roll with a 45° vacuum section wasinstalled and attached to a variable vacuum pump. The vacuum section waspositioned at the contact point of extrudate and greige goods. The niproll pressure was set at 80 psi and the chill roll was controlled at120° F. (49° C.). Secondary backing material (2.8 OSY 99 cm³/m²) wovenpolypropylene scrim or Action Bac® available from Amoco ChemicalCompany, Fabrics and Fibers Division) was added to the backside of thecarpet samples after disposition of the extrudate at the die and beforethe nip pressure rollers to form a laminate structure. After coatedsamples were aged for 24 hours at ambient and 70% relative humidity,tuft bind, abrasion resistance and delamination resistance weredetermined.

TABLE 4 Coat Melt Line Pre-Temp Weight Temp Screw Speed Vac Tuft Bind °F. Thick OSY ° F. Speed ft/min in H₂O Lamination lbs. Ex. Resin (° C.)mil (cm³/m²) (° C.) rpm (m/min) (Pa) Flex Strength (kg) 23 C Ambient ND11.6 500 20 18  0 Good Good 8.6 (410) (260) (5.5) (3.9) 24 C Ambient ND14.2 500 25 18  0 Good Good 7.9 (502) (260) (5.5) (3.6) 25 C Ambient ND17.8 500 30 18  0 Good Good 10.1  (630) (260) (5.5) (4.6) 26 B AmbientND  9.7 500 20 18  0 Good Good 9.0 (343) (260) (5.5) (4.1) 27 B AmbientND 13.0 500 25 18  0 Good Good 7.0 (460) (260) (5.5) (3.2) 28 B AmbientND 14.2 500 30 18  0 Good Good 9.1 (502) (260) (5.5) (4.1) 29 G 200 ND 6.9 400 ND 18  0 Good Good 6.6 (93) (244) (204) (5.5) (3.0) 30 G 200 ND11.8 400 ND 18  0 Good Good 8.4 (93) (417) (204) (5.5) (3.8) 31 H 200 ND10.2 400 ND 18  0 Good Good 7.3 (93) (361) (204) (5.5) (3.3) 32 B 150 ND 8.0 500 24 26 20 Good Good ND (66) (283) (260) (7.9) (4.9) 33 B 150 ND 7.7 500 24 26 10 Good Good ND (66) (272) (260) (7.9) (2.5) 34 B 150 ND 7.8 500 24 26  0 Good Good ND (66) (276) (260) (7.9) 35 B 150 ND  3.9500 48 26  0 Good Good ND (66) (138) (260) (7.9) 36 B 150 ND 15.8 500 4826 10 Good Good 8.7 (66) (559) (260) (7.9) (2.5) (3.9) 37 B 150 ND 15.4500 48 26 25 Good Good 9.6 (66) (545) (260) (7.9) (6.1) (4.4) 38 B 150ND 14.8 550 48 26 25 Good Good 7.6 (66) (523) (288) (7.9) (6.1) (3.4) 39B 150 ND 18.0 550 48 26 20 Good Good 8.2 (66) (637) (288) (7.9) (4.9)(3.7) 40 G 175 ND 10.7 400 26 26 25 Good Good ND (79) (378) (204) (7.9)(6.1) 41 G 175 ND  9.2 400 26 26 10 Good Good ND (79) (325) (204) (7.9)(2.5) 42 G 175 ND  9.5 400 26 26 2.5  Good Good ND (79) (336) (204)(7.9) (0.6) 43 G 175 ND 27.2 400 55 26 2.5  Good Good 10.9  (79) (962)(204) (7.9) (0.6) (4.9) 44 G 175 ND 26.0 400 55 26 10 Good Good 8.8 (79)(920) (204) (7.9) (2.5) (4.0) 45 G 175 ND 17.8 400 55 26 25 Good Good10.2  (79) (630) (204) (7.9) (6.1) (4.6) 46 C 250 ND  9.8 500 24 26 25Good Good 10.9  (121)  (347) (260) (7.9) (6.1) (4.9) 47 C 250 ND  9.6500 24 26 10 Good Good 9.9 (121)  (340) (260) (7.9) (2.5) (4.5) 48 C 250ND  9.3 500 24 26 2.5  Good Good ND (121)  (329) (260) (7.9) (0.6) 49 C250 ND 16.6 500 51 26 2.5  Good Good 6.8 (121)  (587) (260) (7.9) (0.6)(3.1) 50 C 250 ND 17.5 500 51 26 10 Good Good 7.0 (121)  (619) (260)(7.9) (2.5) (3.2) 51 C 250 ND 16.6 500 51 26 25 Good Good 7.6 (121) (587) (260) (7.9) (6.1) (3.4) 52 C 245 ND 10.2 500 50 26 50 Good Good7.8 (118)  (361) (260) (7.9) (12.3)  (3.5) 53 C 245 ND 19.8 500 50 26 50Good Good 10.8  (118)  (700) (260) (7.9) (12.3)  (4.9)  54* L 200 15 ND400 ND 18  0 Stiff Poor ND (93) (0.38) (204) (5.5) *Denotes ComparativeRun Example; the example is not an example of the preferred embodimentof the present invention. ND = value was not determined.

These Examples show that homogeneously branched ethylene polymers resultin carpet samples with good flexibility and good cohesion of carpetcomponents, and that tuft bind strength and abrasion resistance aredependent on processing conditions. These Examples also show theimprovement in carpet backing performance is attainable by theutilization of a carpet preheating process step, optimized coatingthickness, and/or a vacuum nip pressure process step.

The high pressure LDPE extrusion coating resin resulted in stiff carpetwith poor component cohesiveness.

Examples 55-77

Table 5 summarizes the polymers, extrusion conditions and carpetperformance results for Examples 55-77. These examples employed the sameextrusion equipment and extrusion conditions listed for Examples 23-54,with the exception that nylon greige goods (26 OSY (920 cm³/m²), tufted,loop pile, straight stitch greige goods available from Shaw Industriesunder the designation of Vocation™) were used instead of polypropylenegreige goods.

TABLE 5 Coat Melt Line Pre-Temp Weight Temp Screw Speed Vacuum ° F. OSY° F. Speed ft/min in H₂O Lamination Ex. Resin (° C.) (cm³/m²) (° C.) RPM(m/min (Pa) Flex Strength 55 C Ambient 18.4 500 25 18  0 Good Good (651)(260) (5.5) 56 C Ambient 18.9 500 30 18  0 Good Good (668) (260) (5.5)57 C Ambient 20.2 500 35 18  0 Good Good (714) (260) (5.5) 58 B Ambient12.1 500 25 18  0 Good Good (428) (260) (5.5) 59 B Ambient 17.2 500 3018  0 Good Good (608) (260) (5.5) 60 B Ambient 18.1 500 35 18  0 GoodGood (640) (260) (5.5) 61 G 200  8.4 400 ND 18  0 Good Good (93) (297)(204) (5.5)  62* L 200 13.6 400 ND 18  0 Poor Poor (93) (481) (204)(5.5) 63 B 150 17.6 550 48 26 22 Good Good (66) (623) (288) (7.9) (5.4)64 B 150 15.1 550 48 26 11 Good Good (66) (534) (288) (7.9) (2.7) 65 B150 16.4 550 48 26 2.5  Good Good (66) (580) (288) (7.9) (0.6) 66 G 17516.9 400 26 26 25 Good Good (79) (598) (204) (7.9) (6.1) 67 G 175 16.6400 26 26 10 Good Good (79) (587) (204) (7.9) (2.5) 68 G 175 17.3 400 2626 2.5  Good Good (79) (612) (204) (7.9) (0.6) 69 G 175  8.0 400 55 262.5  Good Good (79) (283) (204) (7.9) (0.6) 70 G 175  8.4 400 55 26 10Good Good (79) (297) (204) (7.9) (2.5) 71 G 175  8.3 400 55 26 25 GoodGood (79) (294) (204) (7.9) (6.1) 72 C 260 18.8 500 24 26 25 Good Good(127)  (665) (260) (7.9) (6.1) 73 C 260 16.6 500 24 26 10 Good Good(127)  (587) (260) (7.9) (2.5) 74 C 260 16.6 500 24 26 2.5  Good Good(127)  (587) (260) (7.9) (0.6) 75 C 260  8.1 500 51 26 2.5  Good Good(127)  (286) (260) (7.9) (0.6) 76 C 260  8.1 500 51 26 10 Good Good(127)  (286) (260) (7.9) (2.5) 77 C 260  7.9 500 51 26 25 Good Good(127)  (279) (260) (7.9) (6.1) ND denotes the value was not determined.

Inventive Examples 55-77 show also that homogeneously branched ethylenepolymers result in carpet samples with good flexibility and goodcohesion of the carpet components, and that tuft bind strength andabrasion resistance are dependent on processing conditions. LikeExamples 23-53, these examples also show that improvements in carpetbacking performance are attainable by employing a preheat process step,optimum coating thickness and/or a vacuum nip pressure process step.

Examples 78-86

Table 6 summarizes the polymers, extrusion conditions and carpetperformance results for Examples 78-86. These examples used the sameextrusion equipment and extrusion conditions listed for Examples 1-12,with the exceptions that cross stitch polypropylene greige goods (20 OSY(707 cm³/m²), tufted, loop pile available from Shaw Industries under thestyle name of “Proton”) were used instead of straight stitch goods

TABLE 6 Pre- Coat Melt Line Tuft Temp Weight Temp Speed Bind ° F. OSY °F. ft/min Lamination lbs. Abrasion Velcro Ex. Resin (° C.) (cm³/m²) (°C.) (m/min) Flex Strength (kg) Resistance Test 78 C Ambient  7.7 500 48Good Good  8.5 Good 8 (272) (260) (14.6)  (3.9) 79 C 175 16.9 500 22Good Good 14.3 Good 9 (79) (598) (260) (6.7) (6.5) 80 E 175  9.9 500 48Good Good 10.2 Good 9 (79) (350) (260) (14.6)  (4.6) 81 E 175 17.3 50022 Good Good 13.2 Good 9 (79) (612) (260) (6.7) (6.0) 82 D 175 17.8 50022 Good Good 12.9 Good 9 (79) (630) (260) (6.7) (5.9) 83 D 175  9.2 50048 Good Good  7.6 Good 9 (79) (325) (260) (14.6)  (3.4)  84* J 175  9.7500 48 Stiff Poor  8.7 Good 9 (79) (343) (260) (14.6)  (3.9)  85* J 17516.3 500 22 Stiff Poor 10.4 Good 9 (79) (577) (260) (6.7) (4.7)  86* JAmbient 18.6 500 22 Stiff Poor  9.1 Good 9 (658) (260) (6.7) (4.1)*Denotes Comparative Run Example; the example is not an example of thepresent invention. ND denotes the value was not determined.

Inventive Examples 78-83 show that homogeneously branched ethylenepolymers result in cross-stitched carpet samples with good flexibilityand good cohesion of the carpet components. The LLDPE extrusion coatingresin used for Comparative Runs 84-86 resulted in stiff cross-stitchedcarpet samples.

Examples 87-90

Table 7 summarizes the polymers, extrusion conditions and carpetperformance results for Inventive Examples 87-90. These examples usedthe same extrusion equipment and extrusion conditions as listed forExamples 23-54, with the exceptions that polypropylene greige goods,namely a 2750 denier polypropylene yarn tufted at 16 OSY (566 cm³/m²) ina loop pile, straight stitch, and available from Shaw Industries underthe style name “Quadratic,” were used instead of polypropylene greigegoods. In addition, for Examples 88-90, the greige goods were coatedwith an olefinic suspension or emulsion, known as a pre-coat, prior toextrusion coating.

In particular, an aqueous dispersion of polyethylene particles wasprepared by weighing out 200 parts water. Next, 0.4 parts of asurfactant from Ciba-Geigy under the designation “Igepal CO-430” wasdispersed in the water using a high speed homogenizer at low speed.Then, 100 parts “FN500” from Quantum Chemical was added to the mixtureusing medium to high mixing speeds for approximately 5 minutes. Afterthe FN500 began agitating, 0.4 parts of a defoamer from Lenmar under thedesignation “Marfoam” were added to reduce the foaming of the mixture.Finally, 2.4 parts of a thickener sold by Sun Chemical Internationalunder the designation “Printgum 600M” was added to the mixture. Aminimum of 10 minutes of mixing was needed after adding this thickener.

This dispersion was applied to the back of the primary backing byconventional means. In particular, 38 OSY (1,344 cm³/m²), based on thewet dispersion, were applied to the non-pile side of the primary backingby a roll over roller applicator running at 10 feet per minute (3.05m/min).

After the dispersion was applied, the carpet passed directly into aconventional high velocity drying oven. The total dwell time in the ovenwas 5 minutes and the carpet reached a final temperature of about 290°F. (143° C.).

Observations made before after the pre-coat was applied, but beforeapplication of an extruded adhesive backing material showed that thecarpet thus produced had good bundle penetration and wrap. Measurementsshowed that 4 and 8 OSY (283 cm³/m²) of the FN500, based on dry weight,were added to the carpet backing.

Before application of an extruded adhesive backing, the carpet ofExamples 88-90 was also tested according to test method ASTM D1335 tomeasure the tuft bind strength of the carpet (See, 1991 Annual Book ofASTM Standards, Volume 07.01). This test measures the force required topull one or both legs of a loop in a loop pile carpet free from thebacking. The carpet made in Example 88-90 showed an average tuft bindstrength of 9.0 pounds (4.1 kg) before application of the extrudedadhesive backing.

Example 87 included a pre-coat of Adcote™ 50T4990, an ethylene acrylicacid copolymer dispersion available from Morton International,Woodstock, Ill. applied at 4 OSY (141.5 cm³/m²).

No vacuum was applied for these Examples.

TABLE 7 Pre- Coat Melt Tuft Temp Pre-Coat Weight Temp bind ° F. Type/OSYOSY ° F. Lamination lbs. Abrasion Velcro Ex. Resin (° C.) (cm³/m²)(cm³/m²) (° C.) Flex Strength (kg) Resist. Test 23 C Ambient None 11.6 500 Good Good  8.6 Poor 2 (410) (260) (3.9) 87 C Ambient Adcote/4 3.9500 Good Good 10.7 Good 8 (141) (138) (260) (4.9) 88 C 175 LDPE/8 8.8500 Good Good  8.2 Good 9 (79) (283) (311) (260) (3.7) 89 E 175 LDPE/4ND 500 Good Good 10.0 Good 8 (79) (141) (260) (4.5) 90 E 175 LDPE/8 5.5500 Good Good 11.3 Good 9 (79) (283) (195) (260) (5.1)

Inventive Examples 87-90 show that homogeneously branched ethylenepolymers result in carpet samples with good flexibility and goodcohesion of the carpet components, and that carpet performance can beenhanced by the application of a pre-coat.

Examples 91-96

Table 8 summarizes the polymers, extrusion conditions, and results forExamples 91-96. These Examples used the same extrusion equipment andextrusion conditions as listed for Examples 23-54, with the exceptionsthat nylon greige goods, namely a 3050 denier nylon 6, tufted at 20 OSY(707 cm³/m²), in a loop pile, straight stitch and available from ShawIndustries under the style name “Vanguard™,” were used instead ofstraight stitch goods and the greige goods were coated with an olefinicsuspension or emulsion (i.e., a pre-coat) prior to the extrusion coatingstep. No vacuum was applied for these Examples. The pre-coats evaluatedincluded Adcote™ 50T4990, an ethylene acrylic acid copolymer dispersionavailable from Morton International, Woodstock, Ill. and a LDPEsuspension wherein for the latter the pre-coated greige goods wasavailable from Shaw Industries under the designation of Vanguard™. Thesepre-coats were applied at 4 (141.5 cm³/m²) and 8 OSY (283 cm³/m²)weights.

TABLE 8 Pre- Coat Melt Tuft Temp Pre-Coat Weight Temp Bind ° F. OSY OSY° F. Lamination lbs. Abrasion Velcro Ex. Resin (° C.) (cm³/m²) (cm³/m²)(° C.) Flex Strength (kg) Resistance Test 91 G 150 Adcote/4 8.7 500 GoodGood 10.7  Good 9 (66) (141) (308) (260) (4.9) 92 G 150 LDPE/8 10.0  500Good Good 7.0 Fair 5 (66) (283) (354) (260) (3.2) 93 G 150 LDPE/8 9.3500 Good Good 5.0 Fair 6 (66) (283) (329) (260) (2.3) 94 G 150 Adcote/46.3 500 Good Good 12.1  Good 8 (66) (141) (223) (260) (5.5) 95 G 150LDPE/8 6.1 500 Good Good 6.3 Good 7 (66) (283) (216) (260) (2.9) 96 G150 LDPE/4 3.2 500 Good Good 9.2 Good 9 (66) (141) (113) (260) (4.2)

These examples show that homogeneously branched ethylene polymers resultin carpet samples with good flexibility and good cohesion of the carpetcomponents, and that carpet performance can be enhanced by theapplication of an aqueous pre-coat.

Examples 97-109

Table 9 summarizes the polymers, extrusion conditions and carpetperformance results for Inventive Examples 97-109. These Examples usedthe same extrusion equipment, extrusion conditions and greige goodslisted for Examples 1-12, with the exception that a dual lip or twostation extrusion coating technique was evaluated. In this evaluation,greige goods were first extrusion coated with a layer next to thebackside of the carpet. This layer was identified as the bottom layer.Once coated, samples were then extrusion coated again with anotherlayer, identified as the top layer.

TABLE 9 Melt Thick Thick Temp Line Tuft Top Bottom Top Speed bind TopBottom mil mil ° F. ft/min Lamination lbs. Ex. Resin Resin (mm) (mm) (°C.) (m/min) Flex Strength (kg) 97 C A 15 5 575 60 Good Good 5.2 (0.38)(0.13) (302) (18.3) (2.4) 98 C C 15 5 575 60 Good Good 4.5 (0.38) (0.13)(302) (18.3) (2.0) 99 C G 15 5 575 60 Good Good 5.5 (0.38) (0.13) (302)(18.3) (2.5) 100 C F 15 5 575 60 Good Good 5.0 (0.38) (0.13) (302)(18.3) (2.3) 101 D A 15 5 625 60 Good Good 7.1 (0.38) (0.13) (329)(18.3) (3.2) 102 D C 15 5 625 60 Good Good 4.9 (0.38) (0.13) (18.3)(2.2) 103 D G 15 5 625 60 Good Good 6.2 (0.38) (0.13) (329) (18.3) (2.8)104 D F 15 5 625 60 Good Good 7.5 (0.38) (0.13) (329) (18.3) (3.4) 105 CA 15 5 625 60 Good Good 8.4 (0.38) (0.13) (329) (18.3) (3.8) 106 C C 155 625 60 Good Good 5.7 (0.38) (0.13) (329) (18.3) (2.6) 107 D A 15 5 62560 Good Good ND (0.38) (0.13) (329) (18.3) 108 D C 15 5 625 60 Good Good7.0 (0.38) (0.13) (329) (18.3) (3.2) 109 C F 15 5 600 90 Good Good 6.8(0.38) (0.13) (316) (27.4) (3.1) ND denotes the value was notdetermined.

Inventive Examples 97-109 show that two station extrusion ofhomogeneously branched ethylene polymers results in carpet samples withgood flexibility and good cohesion of the carpet components. The toplayer can also contain fillers or recycled polymeric materials to modifyproperties or for cost savings.

Examples 110-117

Table 10 summarizes the polymers, extrusion conditions and carpetperformance results for Inventive Examples 110-117. These Examples usedthe same extrusion equipment, greige goods and extrusion conditions aslisted for Examples 1-12, with the exception that a single diecoextrusion technique was used. Different candidate ethylene polymerswere introduced into both extruders, respectively. The ethylene polymerswere then fed simultaneously into a single die and coextruded onto thebackside of the greige goods. The layer extruded onto the backside ofthe carpet (i.e., adjacent to the primary backing material) wasidentified as the bottom layer, while the outer layer was identified asthe top layer. Different thicknesses were evaluated and different melttemperatures were used.

TABLE 10 Melt Melt Thick Thick Temp Temp Line Tuft Top Bottom Top BottomSpeed Bind Top Bottom mil mil ° F. ° F. ft/min Lamination lbs. Ex. ResinResin (mm) (mm) (° C.) (° C.) (m/min) Flex Strength (kg) 110 C A 15 5525 475 22 Good Good 8.2 (0.38) (0.13) (274) (246) (6.7) (3.7) 111 C G15 5 525 475 22 Good Good 7.8 (0.38) (0.13) (274) (246) (6.7) (3.5) 112C F 15 5 525 475 22 Good Good 8.1 (0.38) (0.13) (274) (246) (6.7) (3.7)113 D F 15 5 525 475 22 Good Good 5.6 (0.38) (0.13) (274) (246) (6.7)(2.5) 114 C A 10 5 525 475 30 Good Good 7.9 (0.25) (0.13) (274) (246)(9.1) (3.6) 115 C G 10 5 525 475 30 Good Good 5.9 (0.25) (0.13) (274)(246) (9.1) (2.7) 116 C F 10 5 525 475 30 Good Good 8.1 (0.25) (0.13)(274) (246) (9.1) (3.7) 117 C F 15 5 550 500 22 Good Good 7.5 (0.38)(0.13) (288) (260) (6.7) (3.4)

Inventive Examples 110-117 show that single die coextrusion ofhomogeneously branched ethylene polymers results in carpet samples withgood flexibility and good cohesion of the carpet components. The toplayer can also contain fillers or recycled polymeric material to modifyproperties or provide for cost savings.

Examples 118-122

As a simulation of extrusion coating, a compression molding method wasdeveloped to melt plaques of candidate resins on to the backside ofgreige goods. This method employs a programmable press. The followinglists the procedure.

Preparation of Ethylene Polymer Plagues:

Ethylene polymer pellets granules or powder were pressed into plaquesweighing approximately 16 grams and having a thickness of 0.025 inches(0.64 mm). The press used was a pneumatic Tetrahedron programmablepress. The polymer pellets, granules or powder were placed between Mylarbrand polyester film in the desired plaque mold and preheated for 30seconds at 374° F. (190° C.) (this was accomplished by inserting thesamples into the pre-heated press and closing the platens sufficientlyto allow for heating of the polymer sample without compressing it).After 30 seconds, the platens were completely closed and the Tetrahedronprogram was started. The program provided 2 tons (1,814 kg) compressionat 374° F. (190° C.) for 1.5 minute and 50 tons (4.5×10⁴ kg) compressionat 100° F. (38° C.) cooling for 5 minutes. Once the program had ended,the sample was removed and further cooled. Samples were then stored forlater use in a compression lamination step with greige good squares.

Preparation of Greige Good Squares:

Greige goods were cut into squares (slightly larger than the size usedto mold the ethylene polymer samples as described above) and taped ontoan insulation board. The sample squares were then preheated for 15minutes in a Hot Pack oven set at 110° C.

Compression Lamination of Ethylene Polymers to Greige Good Squares:

Ethylene polymer plaques as prepared above were placed on Mylar brandpolyester film and set into the preheated press (374° F.) (190° C.) for5 minutes. The press platens were closed sufficiently to pre-heat theplaques without compressing them. The greige good squares, which hadbeen preheated for about 5 minutes at about 374° F. (190° C.), were thentaken from the Hot Pack oven and introduced to the press (i.e., invertedonto preheated polymer plaques. At the instant the polymer plaques andgreige good squares were married, approximately 0.1 ton (90.7 kg) offorce was applied and then the press was immediately opened. Thelaminated samples were then taken out of the press and allowed to coolto ambient room temperature. The amount of time required to compressionlaminate the greige good squares and the polymer plaques was about 3-7seconds.

Table 12 gives molding conditions and performance results for varioushomogeneously branched substantially linear ethylene polymers.

TABLE 12 Example Resin Tuft bind lbs. (kg) 118 C 17.7 (8.0) 119 B 14.3(6.5) 120 A 11.2 (5.1) 121 G 17.5 (7.9) 122 H 12.8 (5.8)

Examples 123-131

To measure the adhesion of candidate ethylene polymers to greige goodsquares, the compression lamination method described for Examples118-122 was used. Peel strengths were then measured using an Instron setat a 25 mm/minute cross-head speed.

Table 13 gives adhesion results for various homogeneously branchedethylene polymers, high pressure LDPE, heterogeneously branched ULDPE,heterogeneously branched LLDPE, and HDPE laminated to squares made frompolypropylene carpet greige goods.

TABLE 13 Adhesion Strength, lbs. Example Resin (kg) 123 E 7.83 (3.6) 124B 4.82 (2.2) 125 C 1.77 (0.8) 126 G 3.19 (1.4) 127 I 4.73 (2.1)  128* P0.40 (0.2)  129* N 1.60 (0.7)  130* O 1.41 (0.6)  131* M 1.79 (0.8) 132* Q 0.49 (0.2) **Denotes Comparative Run Example; the example is notan example of the preferred embodiment of the present invention.

These Examples show that homogeneously branched substantially linearethylene polymers and homogeneously branched linear ethylene polymersprovide superior adhesion relative to ordinary polyolefin resins and assuch result in enhanced performance when used as adhesive backingmaterials.

Intimate Contact and Substantial Encapsulation

The interface of carpet sample cross-section were captured inphotomicrographs using a scanning electron microscope to assess theadhesive interaction between various carpet components. FIG. 3 is aphotomicrograph of the interface cross-section of Example 18 at 20× and50× magnifications. FIG. 4 is a photomicrograph of the interfacecross-section of Example 22 at 20× and 50× magnifications. WhereasExample 18 was found to possess only fair carpet performance, Example 22was found to possess relatively good carpet performance. The improvedperformance of Example 22 is attributed to the enhanced intimate contactbetween the adhesive backing material and the primary backing materialand to the substantial encapsulation of fiber bundles due to enhancedbundle penetration. The enhanced bundle penetration of Example 22relative to Example 18 is clearly evident when comparing FIG. 3 and FIG.4.

Percent Bundle Penetration

To quantify bundle penetration, digital image analysis was performedusing a Quantimet 570 imager available from Leica, Inc. Deerfield, Ill.and running Version 2.0 QUIC software. Digital images were obtained froma scanning electron microscope through a Sanyo VDC 3860 CCD video cameraequipped with a Javelin 12.5-75 mm zoom lens.

The total cross-section area of a fiber bundle was defined by tracingover the digital image using the binary edit feature of the QUICsoftware. The void cross-section area (i.e., area of no backing materialpenetration) of the bundle was determined in the same manner as for thetotal cross-section area. Bundle penetration was then calculated as oneminus the ratio of void to bundle areas.

FIG. 5 shows the relationship of between bundle penetration and tuftbind strength for nylon and polypropylene carpets. Extrusion coatedethylene polymer bundle penetrations greater than 40 percent, preferablygreater than or equal to 60 percent, more preferably greater than orequal to 80 percent and most preferably greater than or equal to 90percent are required for good carpet performance.

Also, FIG. 5 indicates that lower fiber bundle penetration levels arerequired for nylon carpet to achieve the same level of abrasionresistance as for polypropylene carpet. Here, the nylon carpet has twoimportant differences relative to the polypropylene carpet. For one, thenylon carpet was washed with a mild aqueous detergent solution as partof the dyeing operation. Secondly, the nylon carpet fibers are polarwhile the polypropylene carpet fibers are nonpolar. However, the resultin FIG. 5 of a lower fiber bundle penetration requirement for the nyloncarpet is unexpected and surprising in that although a nonpolar adhesivebacking material is employed, high abrasion performance appears to beobtained easier with a washed or scoured polar carpet (i.e., nylon)relative to the nonpolar carpet (i.e., polypropylene). Ordinarily, oneskilled in the art would expect like materials to better attract oneanother and thereby require less penetration of the adhesive backingmaterial into the fiber bundles for a given level of abrasionresistance. This result is also surprising in that homogeneouslybranched ethylene polymers have been shown in U.S. Pat. No. 5,395,471,the disclosure of which is incorporated herein by reference, to exhibitimproved adhesion to polypropylene substrates yet here better resultsare obtained for nylon fibers over polypropylene fibers. These resultsindicated that selection of the adhesive backing material for mechanicalbonding and a scouring or washing process step can compensate for thelack of or reduced chemical interactions between the various carpetcomponents.

Examples 33-141

To indicate the relative ability of candidate ethylene polymers topenetrate carpet yarn or fiber bundles at reasonable processingtemperatures and thereby provide good carpet performance, solidificationtemperature testing was performed. In this test, candidate ethylenepolymers were tested in the Temperature Sweep mode on a RheometricsMechanical Spectrometer 800E (S/N 035-014) fitted with a cone/cylinderfixture. The dimensions of the fixture were 52 mm (cup insidediameter)×50 mm (bob outside diameter)×17 mm (bob height)×0.04 (coneangle). The gap between the bob and cup was calibrated to 50 μm±2 μm atroom temperature and zero gap at 220° C. Samples were loaded into thecup and heated until molten. The gap was set to 50 μm±2 μm as soon asthe bob was pushed in. Any excess amount of samples or overflow wascleaned away. The solidification measurement was initiated when the tooltemperature reached 220° C. The cup was oscillated at 1 Hz and 20%dynamic strain. The experiment proceeded by a first slow cool rate from220° C. to 110° C. at a 10° C./step. Samples were treated to a secondslow cool rate of 5° C./step from 110° C. to 40° C. To prevent anycontraction of the fixture, auto-tension was applied to keep the normalforce slightly above zero. The auto-tension was set as: 5 gram(pre-tension), 1 gram sensitivity and 100 dyne/cm² (1.02 kg/m²) lowlimit. When samples solidified, high torque was suddenly generated. Anauto-strain was applied to prevent transducer from overloading beforethe sample was completely solidified. The auto-strain was set as: 100%maximum applied strain, 100 g-cm maximum allowed torque, 10 g-cm minimumallowed torque and 50% strain adjustment. The entire experiment wasconducted in a dried nitrogen environment to minimize sampledegradation.

Table 14 gives solidification temperatures for homogeneously branchedethylene polymers and a high pressure LDPE extrusion coating resin.

TABLE 14 Example Resin Solidification Temp, ° C. 133 B 83 134 C 91 135 G94 136 E 76 137 H 95 138 A 70 139 F 71 140 I 77  141* S 106 *DenotesLDPE resin.

These Examples show that homogeneously branched ethylene polymers haverelative low solidification temperatures and, as such, a better abilityto penetrate carpet yarns or fiber bundle compared to ordinary lowdensity polyethylenes. Olefin polymers suitable for use in the presentinvention are thought to have solidification temperatures less than 100°C., preferably less than or equal to 90° C., more preferably less thanor equal to 85° C., and most preferably less than or equal to 80° C. Incertain embodiments of the present invention, the solidificationtemperature of the olefin extrusion coating resin, wherein homogeneouslybranched ethylene polymers are preferred, is in the range of from about65 to about 100° C., preferably from about 70 to about 90° C. and morepreferably from about 70 to about 85° C.

Examples 142-152 Scouring and Washing

In another evaluation, a wet vacuum scouring and washing technique wasinvestigated to determine its effect on the performance of adhesivebacking materials of the present invention.

The evaluation consisted of two different wet vacuuming procedures. Thefirst wet vacuuming procedure (denoted Vac #1 in the table below)consisted of cleaning the backside of greige good samples (i.e., theprimary backing material side as opposed to the fiber face side) using acommercial wet vacuum carpet cleaner equipped with a dispensing/filltank, Rinsenvac™ Carpet Cleaning System supplied by Blue LustreProducts, Inc., Indianapolis, Ind., filled to dispense ambienttemperature tap water as the cleaning solution. When the first wetvacuuming procedure was used, the greige good samples were subjected totwo separate wet vacuum cleanings and were completely air dried aftereach cleaning. The second wet vacuuming procedure (denoted Vac #2 in thetable below) consisted of cleaning the backside of greige good samplesusing the Rinsenvac™ Carpet Cleaning System filled to dispense a hot(90° C.) aqueous solution of dilute Rinsenvac™ Professional CarpetCleaner as the cleaning solution mixture. The concentration of thecleaning solution for the second wet vacuuming procedure was 10 partstap water to 1 part Rinsenvac™ detergent. When the second wet vacuumingprocedure was used, the greige good samples were subjected to one wetvacuum cleaning followed by complete air drying, a rinse using ambienttemperature water and then a final complete air drying step. For eachwashing procedure, 0.5 gallons (1.9 liters) of cleaning solution wasdispensed per 5 yd² (4.2 m²) of greige goods.

In this evaluation, unwashed (control samples) and washed tufted greigegood samples were extrusion coated using a monolayer die configuration,although a single die coextrusion and dual lip coextrusion can also beused. Auxiliary equipment included: pre-heaters and heat soak ovens.

The extrusion coating equipment consisted of a two-extruder BlackClawson coextrusion line with a 3½ inch (8.9 cm) diameter primaryextruder with a 30:1 L/D and a 2½ inch (6.4 cm) diameter secondaryextruder with a 24:1 L/D. For these examples, only the large extruderwas operated at variable rates. A 76 cm slot die is attached and deckledto 69 cm with a 20 mil (0.51 mm) die gap and a 6 inch (15.2 cm) air/drawgap. The nip roll pressure was set at 30 psi (0.2 MPa) and the chillroll temperature was varied.

The greige good were swatches of Volunteer™ carpet supplied by ShawIndustries. Volunteer™ carpet consists of polypropylene fibers at 26oz/yd² (920 cm³/m²) and is characterized as a tufted, loop pile, singlestitch carpet. Both control unwashed and washed greige good samples wereslip sheeted onto Kraft paper during extrusion coating to apply theadhesive backing material. Both unwashed control samples and washedsamples were first preheated in a convection oven prior to applying theextrusion coated adhesive backing material.

A substantially linear ethylene polymer, designated XU-59100.00 assupplied by The Dow Chemical Company, was used as the adhesive backingmaterial in this evaluation. XU-59100.00 is characterized as having a 30g/10 min. melt index and a 0.900 g/cc polymer density. The pre-heatmeasured temperature was set at 160° F. (71° C.), extrusion coating melttemperature was set at 500° F. (260° C.), the chill roll temperature wasset at 80° F. (27° C.) and the extrusion coating line speed was set at85 ft/min (26 m/min).

After the extrusion coated samples were allowed to age for at least 24hours at ambient room temperature, tuft bind, abrasion resistance anddelamination performance were measured. Tuft bind testing was conductedaccording to ASTM D-1335-67. Abrasion resistance results were obtainedusing a Velcro test procedure wherein a 2 inch (51 mm) diameter, 2 pound(0.91 kg) roller coated with the loop side of standard Velcro was passed10 times over the face side of coated carpet samples. The fuzz on theabraded carpet was then compared to a set of carpet standards and ratedon a 1-10 scale (10 denoting zero fuzz). Abrasion resistance was alsoquantified using the Fiber Lock Test which is described hereinbelow. Ingeneral, if the Velcro Number was below 6 or the abrasion resistance ofthe carpet sample was rated poor, tuft binds were not measured. Thefollowing Table 15 summarizes the results of this evaluation.

TABLE 15 Ex- Resin Coating Tuft Bind Velcro Fiber am- Wet Wt. - oz/yd²lbs. Rating Lock ple Vacuuming (cm³/m²) (kg) Number. Fuzz No. 142 None 5.0 ND 0.5 385 (177) 143 None  7.2 ND 4.3 220 (255) 144 None 11.3 7.47.5 78 (400) (3.4) 145 None 10.4 8.5 7.4 81 (368) (3.9) 146 Vac #1  5.57.4 8 60 (195) (3.4) 147 Vac #1  8.0 7.4 8 61 (283) (3.4) 148 Vac #110.6 7.7 9 25 (375) (3.5) 149 Vac #1 11.0 6.7 8 40 (389) (3.0) 150 Vac#2  7.1 8.3 8 76 (251) (3.8) 151 Vac #2  7.9 8.8 8 52 (279) (4.0) 152Vac #2 10.2 8.4 8 42 (361) (3.8)

The results in Table 15 show that, at equivalent adhesive backingmaterial coating weights, the use of a wet vacuuming process step priorto the application of the adhesive backing material can significantlyimprove carpet performance relative to unwashed samples. The improvementis so dramatic that substantially reduced adhesive backing materialcoating weights can be used while maintaining excellent tuft bind andabrasion resistance.

Examples 153-163 Implosion Agents and High Heat Content Fillers

In another evaluation, tufted greige good samples were extrusion coatedto evaluate the effect of calcium carbonate as a high heat contentfiller and a conventional blowing agent (i.e., azodicarbonamide) whenemployed as an implosion agent. The calcium carbonate and theazodicarbonamide were dry-blended with a substantially linear ethylenepolymer according the weight percentage shown in the table immediatelybelow. The substantially linear ethylene polymer had 30 g/10 min. Meltindex and a 0.885 g/cc density and was supplied by The Dow ChemicalCompany under the designation XU-59400.00. The azodicarbonamideimplosion agent was Epicell #301 which was supplied as a 30 weightpercent concentrate in low density polyethylene by EPI Chemical Company.The calcium carbonate which had a specific heat capacity of about 0.548cal-cc/° C. (2.3 Joules-cm³/° C.) was supplied as a 75 percent weightconcentrate in low polyethylene by Heritage Bag Company.

Volunteer™ greige goods supplied by Shaw Industries was used in thisevaluation. The greige goods were polypropylene fibers, 26 oz/yd² (920cm³/m²), tufted, loop pile, single stitch carpet swatches which were cutand slip sheeted onto Kraft paper for each sample such that each exampleadhesive backing material was extrusion coated onto the back side of thecarpet (i.e., onto the primary backing material of the carpet swatches).For each sample, prior to extrusion coating on the adhesive backingmaterial, the greige goods were first preheated in a convection oven.

In this evaluation, the extrusion coating die configuration wasmonolayer and auxiliary equipment included pre-heaters and heat soakovens. Specifically, the extrusion coating equipment consisted of atwo-extruder Black Clawson coextrusion line with a 3½ inch (8.9 cm)diameter primary extruder with a 30:1 L/D and a 2½ inch (6.4 cm)diameter secondary extruder with a 24:1 L/D. However, in thisevaluation, only the large extruder was operated at variable rates. A 76cm slot die was attached to the extruder and deckled to 69 cm with a20-mil (0.51 mm) die gap and a 6-inch (15.2 cm) air/draw gap. The niproll pressure was set at 30 psi (0.2 MPa) and the chill roll temperaturewas varied. The greige goods pre-heat temperature was set at 160° F.(71° C.), the extrusion melt temperature was set at 550° F. (288° C.)and the line speed was 75 ft/min (23 m/min). The chill roll temperaturewas set at 100° F. (38° C.) for the sample that contained no implosionagent and was set at 70° F. for samples containing the implosion agent.

After the extrusion coated samples were aged for at least 24 hours, theywere tested for tuft bind, abrasion resistance, Velcro rating, fuzzrating, flexibility and delamination resistance. Tuft bind testing wasconducted using ASTM D-1335-67. Abrasion resistance and Velcro testingwere based on qualitative tests wherein a 2 inch (51 mm) diameter, 2pound (0.91 kg) roller coated with the loop side of standard Velcro waspassed 10 times over the face side of each extrusion coated samples toabrade the sample. The fuzz on the abraded carpet was then compared to aset of standards and rated on a 1-10 scale (10 denoting zero fuzz).

To provide quantitative abrasion results, a Fiber Lock Test was used. Inthis test, the abrasion resistance value is taken as the “Fiber LockFuzz Number.” The test involves cutting away abraded fibers with a pairof Fiskars 6″ spring-loaded scissors and comparing sample weights beforeand after abraded fibers are removed. Specifically, the Fiber Lock Fuzztest is performed by providing 8 inches (203 mm) cross direction×10inches (254 mm) machine direction extrusion coated samples; clamping thesamples such that they remain flat during double rolling; double rollingthe samples in the machine direction 15 times at a constant speed and atabout a 45° angle using the Velcro roller discussed above in thisevaluation; using a 2 inches×2 inches (51 mm×51 mm) sample cutterattached to a press punch certified by National Analytical EquipmentFederation (NAEF) to provide two test specimens for each sample;weighing and recording the sample weights for each sample to 0.1 mgusing a calibrated AE200 balance; carefully removing all abraded fiberusing a pair Fiskars 6″ spring-loaded scissors while avoiding cuttingany part of a fiber loop; reweighing and recording the two test samples;and taking the difference in weight before and after removal of theabraded fiber as the Fiber Lock Fuzz Number (FLFN). Note that Fiber LockFuzz numbers relate inversely to Velcro Numbers; that is, whereas higherVelcro numbers are desirable as indicative of improved abrasionresistance, lower Fuzz numbers indicate improved abrasion resistance.Table 16 provides the weight percentage of additive and the carpetperformance results.

TABLE 16 Implosion Resin Coating Filler Wt. Tuft Bind Agent FillerAmount Wt. - oz/yd² oz/yd² lbs. Velcro Fiber Lock Example % active %(cm³/m²) (cm³/m²) (kg) Rating No. Fuzz No. 153 0 0 9.3 NA 7.1 5 157(329) (3.2) 154 0.5 0 10.0  NA 7.6 7 91 (354) (3.4) 155 1.0 0 9.4 NA 6.28 52 (332) (2.8) 156 1.5 0 9.7 NA 6.7 7 80 (343) (3.0) 157 0 0 7.4 NA8.1 3 261 (262) (3.7) 158 0 45 8.1 6.6 7.8 7 99 (286) (233) (3.5) 159 060 6.4 9.6 8.1 6 125 (226) (340) (3.7) 160 0 0 9.3 NA 7.1 3 261 (329)(3.2) 161 0.5 15 9.6 1.7 9.0 7 90 (340)  (60) (4.1) 162 0.5 30 8.9 3.98.7 7 108 (315) (138) (3.9) 163 0.5 45 8.0 6.6 7.5 8 73 (283) (233)(3.4)

All examples in this evaluation exhibited good flexibility and exampleswith a Velcro number of at least 6 all exhibited good delaminationresistance. The examples wherein the implosion agent was used all hadclosed cells and a collapsed adhesive backing material matrix i.e., thethickness of the adhesive backing material layer was about same with andwithout the implosion agent. Table 16 shows that the use an implosionagent and a high heat content filler either separately or in combinationsignificantly improves both the tuft bind and abrasion resistance ofextrusion coated carpet compared to an equivalent coating weight ofresin without these additives. Also, Table 16 surprisingly indicatesthat the use of these additives allow improved performance at reducedadhesive backing material coat weights.

Examples 164-175 Adhesive Polymeric Additives

In another evaluation, an unmodified control adhesive backing materialsample and two adhesive backing material samples modified by theaddition of maleic anhydride grafted ethylene polymer were extrusioncoated onto tufted greige goods using a monolayer die configuration,although a single die coextrusion and dual lip coextrusion can also beused. Auxiliary equipment included: pre-heaters and heat soak ovens.

The extrusion coating equipment consisted of a two-extruder BlackClawson coextrusion line with a 3½ inch (8.9 cm) diameter primaryextruder with a 30:1 L/D and a 2½ inch (6.4 cm) diameter secondaryextruder with a 24:1 L/D. For these examples, only the large extruderwas operated at variable rates. A 76 cm slot die was attached anddeckled to 69 cm with a 20 mil ((0.51 mm) die gap and a 6 inch (15.2 cm)air/draw gap. The nip roll pressure was set at 30 psi, the chill rolltemperature was set at 75-80° F. (24-27° C.) and the extrusion linespeed was at 75 ft/min (23 m/min). Prior to application of the adhesivebacking material, the greige goods were pre-heated to about 210° F. (99°C.) in a convection oven and the extrusion melt temperature was 595-610°F. (313-321° C.).

The unmodified control adhesive backing material was a substantiallylinear ethylene polymer having 30 g/10 min. melt index and a 0.885 g/ccdensity as supplied by The Dow Chemical Company under the designationXU-59400.00. To prepare two modified adhesive backing materials,XU-59400.00 was dry-blended with 10 weight percent of two differentmaleic anhydride/ethylene polymer grafts, each containing 1.0 weightpercent maleic anhydride, to provide a final concentration of 0.1 weightpercent maleic anhydride for the two blends. The grafts themselves wereprepared following procedures described in U.S. Pat. No. 4,762,890. Onegraft designated MAH-1 in Table 17, utilized a high density polyethyleneas the host ethylene polymer. The other graft, designated MAH-2 in Table17, utilized a substantially linear ethylene polymer as the hostethylene polymer.

The greige goods were swatches of Vocation 26™ carpet supplied by ShawIndustries. Vocation 26™ carpet consists of nylon fibers at 26 oz/yd²(907 cm³/m²) and is characterized as a tufted, loop pile, single stitchcarpet. The greige good samples were slip sheeted onto Kraft paperduring extrusion coating to apply the control adhesive backing materialand the two modified adhesive backing materials. No secondary backingmaterial was added to the backside of the samples after application ofthe adhesive backing materials, although such can also be used.

After the extrusion coated samples were allowed to age for at least 24hours at ambient room temperature, tuft bind, abrasion resistance anddelamination performance were measured. Tuft bind testing was conductedaccording to ASTM D-1335-67. Abrasion resistance results were obtainedusing the Velcro test procedure described above wherein a 2 inch (51 mm)diameter, 2 pound (0.91 kg) roller coated with the loop side of standardVelcro was passed 10 times over the face side of coated carpet samples.The fuzz on the abraded carpet was then compared to a set of carpetstandards and rated on a 1-10 scale (10 denoting zero fuzz). Abrasionresistance was also quantified using the Fiber Lock Test describedabove. In general, if the Velcro Number was below 6 or the abrasionresistance of the carpet sample was rated poor, tuft binds were notmeasured. The following Table 17 summarizes the results of thisevaluation.

TABLE 17 Resin Coating Velcro Fiber MAH Wt. - oz/yd² Tuft Bind RatingLock Example Type (cm³/m²) lbs. Number. Fuzz No. 164 None 3.7 (131) 5.36 148 165 None 4.9 (173) 5.2 6 161 166 None 6.0 (212) 5.6 4 218 167 None8.7 (308) 7.3 6 136 168 MAH-1 3.4 (120) 5.2 5 197 169 MAH-1 4.9 (173)7.0 5 131 170 MAH-1 6.4 (226) 8.4 7 102 171 MAH-1 8.7 (308) 9.0 7 93 172MAH-2 3.6 (127) 5.7 5 200 173 MAH-2 5.2 (184) 5.5 6 128 174 MAH-2 7.9(279) 9.1 7 81 175 MAH-2 8.6 (304) 8.2 7 110

The results in Table 17 show that the incorporation of maleic anhydrideethylene polymer grafts, wherein either a high density polyethylene(HDPE) or a substantially linear ethylene polymer is employed as thehost resin, permit significant improvements in comparative tuft bindstrength and abrasion resistance. One advantage of these improvements isnow practitioners can employ reduced thermoplastic adhesive backingmaterial coat weights for purposes of cost-savings and still maintaindesired levels of high performance.

Examples 176-181 Aqueous Dispersion Backing Without Further Backing

Example 176 was the same as example 88 above except that there was noadhesive backing extruded onto the carpet. The carpet thus produced hadgood bundle penetration and wrap. Measurements showed that about 12 OSY(424 cm³/m²) of the FN500, based on dry weight, were added to the carpetbacking. The carpet was also tested according to test method ASTM D1335to measure the tuft bind strength of the carpet (See, 1991 Annual Bookof ASTM Standards, Volume 07.01). This test measures the force requiredto pull one or both legs of a loop in a loop pile carpet free from thebacking. The carpet made in Example 176 showed an average tuft bindstrength of 9.0 pounds (4.1 kg).

Example 177 was the same as example 176 except for the followingchanges: First, a defoamer was not used in the dispersion. SecondAerosil A300 from Degussa was added to the dispersion at 0.5 parts.Third, an HDPE from Dow Chemical Co. under the designation DOW 12065HDPE was used in the place of FN500. Fourth, a surfactant under thedesignation DA-6 from Sun Chemical International was used in place ofthe CO-430. Finally, the carpet was dried in a Blue M forced airconvection oven at 270° F. (132° C.) for 30 minutes. The add-on for theHDPE was 8.6 OSY (304 cm³/m²). The average tuft bind strength wasmeasured at 4.0 pounds (1.8 kg).

Example 178 was the same as example 177 except that the Aerosil A-300was removed and that, instead of the HDPE, an ethylene vinyl acetate(EVA) polymer from Quantum under the designation FE-532. The add-on forthe EVA was 10 OSY (354 cm³/m²). The average tuft bind strength for theresulting carpet was measured at 8.2 pounds (3.7 kg).

Example 179 was the same as example 178 except that, instead of the EVA,a polyethylene from Quantum under the designation MRL-0414 was used. Theadd-on for the polyethylene was 3 OSY (106 cm³/m²) and the average tuftbind strength was measured at 2.3 pounds (1.04 kg).

Example 180 was the same as example 177 except that add-on for the FN500was 5.4 OSY (191 cm³/m²). The tuft bind strength was measured at 5.2pounds (2.4 kg).

Example 181 was the same as example 180 except that, instead of theIgepal CO-430, a surfactant under the designation OT-75 from SunChemical International was used. The add-on for the FN500 was 10.5 OSY(371 cm³/m²) and the average tuft bind strength was 4.3 pounds (1.95kg).

Examples 182-193 Dispersion Backings with Further Backings Applied

Examples 182-193 were performed to demonstrate different secondarybackings applied to the carpet made in Example 176.

In Example 182, a piece of carpet made in Example 176 received asecondary backing by placing a coextruded sheet of ethylene vinylacetate/polyethylene from Quantum Chemical Co. under the designationNA202 UE635 on top of the non-pile side of the carpet. The pre-extrudedsheet was 23 mil (0.58 mm) thick. The carpet was then placed in agravity convection oven set at 300° F. (149° C.) for 30 minutes so as tocause the sheet to melt and bond to the back of the precoated carpet.The carpet was then allowed to cool to ambient temperatures.

Examples 183-185 were performed the same as Example 182 with theexception that the sheet of Quantum NA202 UE635 was 35, 37 and 50 mil(0.89, 0.94 and 1.3 mm) thick, respectively.

Example 186 was performed by taking the carpet from Example 176 andapplying a calcium carbonate filled VAE latex over the back of thecarpet. The carpet was then placed in a gravity convection oven at 300°F. (149° C.) for 30 minutes to dry the VAE. The coating weight was about25 OSY (884 cm³/m²), based on dry weight.

Example 187 was performed the same as Example 186 except that the latexwas an unfilled VAE latex. In particular, this latex was purchased fromReichold Chemical Co. under the designation Elvace 97808.

Example 188 was performed the same as Example 186 with the exceptionthat a calcium carbonate filed Styrene Butadiene Rubber (SBR) latex wasused in place of the VAE latex. The SBR latex was applied so as to acoating weight of about 25 OSY (884 cm³/m²).

Example 189 was performed by taking carpet from Example 176 andspreading an EVA powder on the back of the carpet. In particular, theEVA powder was from DuPont under the designation Elvax 410 and wasapplied at 10 OSY (354 cm³/m²).

Example 190 was performed the same as Example 189 with the exceptionthat the powder was a polyolefin wax supplied by Hercules under thedesignation Polywax 2000.

Example 191 was performed by taking the carpet from Example 176 andapplying a compounded hot melt adhesive to the back of the carpet. Inparticular, the hot melt consisted of filled EVA and Piccovar CB-20 fromHercules, Inc. and was applied to the carpet at 30 OSY (1,061 cm³/m²)and at a temperature of about 300° F. (149° C.).

Example 192 was performed the same as Example 191 with the exceptionthat a urethane foam pad was laminated to the carpet backing through thehot melt. In particular, a polyurethane foam pad, available from ShawIndustries under the designation Duratech 100, was laminated with thehot melt.

Example 193 was performed in accordance with the preferred embodiment ofthe aqueous pre-coat aspect of the present invention. A sample of carpetfrom Example 176 had a sheet of a polymer extruded directly onto theback. The polymer used was the polyethylene elastomer provideddesignated “G” in Table 1 above. The density of this particular polymerwas about 0.90 g/cc. The melt index was 75.

A Marsden propane fired infrared heater was used to preheat thesubstrate. The heater was set at temperatures between about 200° F. (93°C.) and about 230° F. (110° C.). The temperature of the carpet wasmeasured at about 145° F. (63° C.) at the point just prior to receivingthe extruded sheet. The polymer was extruded at a 7 mil (0.18 mm)thickness using a typical extrusion coating setup used for papercoating. In particular, a typical polyethylene type extruder was usedwith temperatures of 350° F. (177° C.) for the first barrel, 375° F.(191° C.) for the second barrel and 400° F. (204° C.) for the remainingbarrels, the manifold and the extrusion die. The die was a slot typethat extruded a curtain of hot polymer onto the back of the carpet. Thecarpet was then placed around a chill roll with the back against thechill roll and with a temperature of 120° F. (49° C.). The line speedwas set to 23 feet per minute (7 m/min). The carpet was pressed at thechill roll with a nip pressure of 45 psi (0.31 MPa). Although not donein this specific example, a fabric, such as a typical polypropylenesecondary backing fabric from Amoco Fabrics & Fibers as “ActionBac®,”can be laminated through the extruded sheet just prior to or at thischill roll.

Examples 194-197 Making Carpet Tile with Reinforcement

Examples 194-197 were conducted to make carpet tile according to thepresent invention.

Example 194 was carried out in accordance with the most preferred methodof making carpet tile. A 6 ft. (1.8 m) wide greige good was provided ina roll. The greige good comprised polypropylene yarn tufted into anon-woven primary backing obtained from Akzo under the name “Colback” (ablend of polyamide and polyester polymers) as cut pile at a face yarnweight of about 45 OSY (1,592 cm³/m²). This greige good was passed belowthe extruder at 17 feet per minute (5.2 m/min). The extruder contained amolten polymer mix having the following composition:

% by wt. Substantially linear ethylene polymer 24 (XU-59400.00 from Dow)Maleic Anhydride Grafted 4 Polyethylene (XU-60769.07 from Dow) CalciumCarbonate Filler (Georgia 59 Marble #9) Tackifier (Hercatac 1148 from 12Hercules) Black Concentrate 1 100

The temperature at the die was about 500° F. (260° C.). About 25 OSY(884 cm³/m²) was applied in a first pass, after which a sheet of areinforcement fabric was laid on top of this first layer of polymer. Thereinforcement fabric in this example was a 3.5 OSY (124 cm³/m²) sheet ofTypar (a non-woven polypropylene fabric available from Reemay as“3351”). After passing over a chill roll, the carpet was rolled up for asubsequent pass through the line to apply a second layer.

In a second pass through the same line, a second layer of the sameextrudate was applied on top of the reinforcement sheet. The totaladd-on, not including the Typar was 49.2 OSY (1,740 cm³/m²).

After cooling, the carpet was cut into 18 inches (45.7 cm) square tilesand tested for Tuft bind, and Aachen dimensional stability. The resultsare shown in the Table 18 below.

Example 195 was performed the same as Example 194 except that a looppile nylon yarn was used for the face yarn at 20 OSY (707 cm³/m²) with astraight stitch and the total add-on was 54.0 OSY (1,910 cm³/m²).

Example 196 was performed the same as Example 195 except that the looppile nylon yarn was tufted at 30 OSY (1,061 cm³/m²) with a shiftedstitch and the total add-on was 52.6 OSY (1,860 cm³/m²).

Example 197 was performed the same as Example 196 except that theprimary backing used was a non-woven polyester fabric sold byFreudenberg as “Lutradur.” The total add-on was 52.3 OSY (1,850 cm³/m²).

TABLE 18 Add-On OSY Tuft bind* Aachen M Aachen XM Ex. # Face Fiber(cm³/m²) lbs. (kg) (% change) (% change) 194 PP 49.2 2.9 −0.023 0.105(1,740) (1.3) 195 Nylon 54.0 4.6 −0.062 0.144 (1,910) (2.1) 196 Nylon52.6 4.2 −0.054 −0.054 (1,860) (1.9) 197 Nylon 52.3 4.7 0.063 0.091(1,850) (2.1) *Yarn broke on Tuft bind test

Examples 198-208 Making Carpet Tile with Reinforcement and VariousSecond Pass Add-On Weights

Examples 198-208 were conducted to make carpet tile with differentadd-on weights for the second pass. In addition, two differentreinforcement materials were tests.

Example 198 was performed the same as Example 194 above with theexception that the extrudate applied in the first pass had the followingcomposition:

% by wt. Substantially linear ethylene polymer 69 (XU-59400.00 from Dow)Calcium Carbonate Filler (Georgia 30 Marble #9) Black Concentrate 1 100

11 OSY (389 cm³/m²) of this extrudate was applied to the back of agreige good that consisted of a polypropylene yarn tufted into a wovenpolypropylene primary backing at about 26 OSY (920 cm³/m²) in a looppattern.

In Examples 198-203, a 3.5 OSY (124 cm³/m²) Typar fabric was embeddedbetween the first layer of extrudate and the second. In Examples204-208, a 1.4 OSY (49.5 cm³/m²) fiberglass scrim from ELK Corp. wasused as the reinforcement layer.

In all of Examples 198-208, the second layer of extrudate, which was puton in a second pass through the same line, had the followingcomposition:

% by wt. Substantially linear ethylene polymer 24 (XU-59400.00 from Dow)Maleic Anhydride Grafted 4 Polyethylene (XU-60769.07 from Dow) CalciumCarbonate Filler (Georgia 59 Marble #9) Tackifier (Hercatac 114876 from12 Hercules) Black Concentrate 1 100

The add-on weight from the second pass was varied as shown below inTable 19. The carpet was cut into tiles and subjected to the Aachendimensional stability test with the results noted below.

While particular preferred and alternative embodiments have beendescribed herein, it should be noted that various other embodiments andmodifications can be made without departing from the scope of theinventions described herein. It is the appended claims which define thescope of the patent issuing from the present application.

TABLE 19 2^(nd) Pass Total Reinforcement Add-On, Add-On, Aachen M OSYOSY OSY (% Aachen XM Ex. # (cm³/m²) (cm³/m²) (cm³/m²) change) (% change)198 Typar 3.5 (124) 29.7 40.7 .059 .061 (1,050) (1,440) 199 Typar 3.5(124) 30.5 41.5 .044 .100 (1,079) (1,468) 200 Typar 3.5 (124) 39.3 50.3−.064 .075 (1,390) (1,779) 201 Typar 3.5 (124) 44.0 55.0 −.106 .014(1,556) (1,945) 202 Typar 3.5 (124) 47.5 58.5 0 .044 (1,680) (2,069) 203Typar 3.5 (124) 56.0 67.0 .003 .067 (1,981) (2,370) 204 f.g. 1.4 (50)41.6 52.6 .083 .070 (1,471) (1,860) 205 f.g. 1.4 (50) 47.3 58.3 .086.014 (1,673) (2,062) 206 f.g. 1.4 (50) 52.3 63.3 .003 .086 (1,850)(2,239) 207 f.g. 1.4 (50) 54.1 65.1 .044 .014 (1,914) (2,303) 208 f.g.1.4 (50) 58.4 69.4 .025 .019 (2,066) (2,455)

1. A recyclable carpet or carpet tile comprising: a. a primary backingmaterial having a face and a back side; b. a plurality of fibersattached to the primary backing material and extending from the face ofthe primary backing material and exposed at the back side of the primarybacking material; c. an adhesive composition, wherein the adhesivecomposition comprises a polymer component comprising from about 80 toabout 99 weight percent based upon total weight of the polymer componentof at least one homogenously branched ethylene polymer characterized ashaving a short chain branching distribution index (SCDBI) of greaterthan or equal to 50 percent, wherein the adhesive composition hassubstantially penetrated and substantially consolidated the fibers,wherein the adhesive composition is not integrally fused to the primarybacking material, and wherein the carpet has a tuft bind of 5 pounds ormore as measured according to ASTM D-1335-67; and d. a secondary backingmaterial adjacent to the adhesive composition, wherein the secondarybacking material comprises at least one homogenously branched ethylenepolymer characterized as having a short chain branching distributionindex (SCDBI) of greater than or equal to 50 percent.
 2. The carpet orcarpet tile of claim 1 wherein the homogeneously branched ethylenepolymer is an interpolymer of ethylene with at least one C₃-C₂₀a-olefin.
 3. The carpet or carpet tile of claim 1 wherein thehomogeneously branched ethylene polymer is a copolymer of ethylene andone C₃-C₂₀ a-olefin.
 4. The carpet or carpet tile of claim 3 wherein theone C₃-C₂₀ a-olefin is selected from the group consisting of propylene,1-butene, 1-isobutylene, 1-pentene, 1-hexene, 4-methyl-1-pentene,1-heptene and 1-octene.
 5. The carpet or carpet tile of claim 4 whereinthe one C₃-C₂₀ a-olefin is 1-octene.
 6. The carpet or carpet tile ofclaim 1 wherein (i) the fibers, primary backing and adhesive compositionall comprise a polyolefin polymer, (ii) the olefin monomer chemistry ofthe polymer component in the adhesive composition differs from that ofthe fibers and the primary backing, and (iii) the carpet includes alabel or literature at the time of sale which represents that the carpetis recyclable without segregation of carpet components.
 7. The carpet orcarpet tile of claim 1 wherein the at least one homogeneously branchedethylene polymer is further characterized as having a singledifferential scanning calorimetry, DSC, melting peak between −30 and150° C.
 8. The carpet or carpet tile of claim 7 wherein the at least onehomogeneously branched ethylene polymer is a substantially linearethylene polymer characterized as having: a. a melt flow ratio,I₁₀/I₂>5.63, b. a molecular weight distribution, M_(w)/M_(n) asdetermined by gel permeation chromatography and defines by the equation:(M _(w) /M _(n))<(I ₁₀ /I ₂)−4.63, and c. a gas extrusion rheology suchthat the critical shear rate at onset of surface melt fracture for thesubstantially linear ethylene polymer is at least 50 percent greaterthan the critical shear rate at the onset of surface melt fracture forthe linear ethylene polymer, wherein the linear ethylene polymer has ahomogeneously branched short chain branching distribution and no longchain branching, and wherein the substantially linear ethylene polymerand the linear ethylene polymer are simultaneously ethylene homopolymersor interpolymers of ethylene and at least one C₃-C₂₀ a-olefin and havethe same I₂ and M_(w)/M_(n) and wherein the respective critical shearrates for the substantially linear ethylene polymer and the linearethylene polymer are measure at the same melt temperature using a gasextrusion rheometer.
 9. The carpet or carpet tile of claim 1 wherein theat least one homogeneously branched ethylene polymer is homogenouslybranched linear ethylene polymer.
 10. The carpet or carpet tile of claim1, wherein the primary backing material consists essentially of apolypropylene material.